;fiv^' 



una 




Edited 




House 

P/ 

Co7ite 
used by 
Whitewa 
Embellis 
Boot IV 
Fi 

Conte 
Re-Welti 
Stitching 
and Shoe 
Howtc 
am 

Coftte 
writer's ( 
Forms o 
Ticket-\\ 

Wood 

Wi 

Conte. 

French P 

Off. Gla2 

and Revi 

Piocesses oi varn^sning vvooa vamisITes. 
Dynamos and Electric Motors. 



Qass 

Book ^'"^"0 



lES 



f "Work. 



APERHANGING, 

has, etc. Tools 
ipera Painting, 
sering a Room. 

Lasting, and 

ots and Shoes. 

Sewing and 

Riveted Boots 

70 Engravings 

. The Sign- 
The Simpler 
a Signboard. 

id Polishing. 



aining Wood. 

, and Spiriting 
Re-polishing 

Floors Stains. 
Ke-pblisRing STiop Fronts. 
With 142 Engravings and Diagrams 



Contents. — Introduction. Siemens Dynamo. Gramme Dynamo. Manchester 
Dynamo. Simplex Dynamo. Calculating the Size and Amount of Wire for 
Small Dynamos. Ailments of Small Dynamo Electric Machines : their Causes 
and Cures. Small Electro-motors without Castings. How to Determine the 
Direction of Rotation of a Motor. How to Make a Shutt'e-Armature Motor. 
Undertype 50- Watt Dynamo. Manchester Type 440- Watt Dynamo. 
Cycle Building: and Repairing. With 142 Engravings and Diagrams. 

Contents. — Introductory, and Tools Used. How to Build a Front Driver. 
Building a Rear-driving Safety. Building Tandem Safeties. Building Front- 
driver Tricycle. Building a Hand Tricycle. Brazing. How to Make and Fit 
Gear Cases. Fittings and Accessories. Wheel Making. Tyres and Methods 
of Fixing them. Enamelling. Repairing. 
Decorative Desigrns of All Ag^es for All Purposes. With 277 

Engravings and Diagrams. 

Contents. — Savage Ornament. Egyptian Ornament. Assyrian Ornament. 
Greek Ornament. Roman Ornament. Early Christian Ornament. Arabic 
Ornament. Celtic and Scandinavian Ornaments. Mediaeval Ornament. 
Renascence and Modern Ornaments. Chinese Ornament. Persian Ornament. 
Indian Ornament. Japanese Ornament. 
Mounting and Framing Pictures. With 240 Engravings, etc. 

Contents.— Making Picture Frames. Notes onArt Frames. Picture Frame 
Cramps. Making Oxford Frames. Gilding Picture Frames. Methods of 
Mounting Pictures. Making Photograph Frames. Frames covered with Plush 
and Cork. Hanging and Packing Pictures. 
Smiths' Work. With 211 Engravings and Diagrams. 

C^«z'^;/2'\.— Forges and Appliances. Hand Tools. Drawing Down and Up- 
setting. Welding and Punching. Conditions of Work : Principles of Forma- 
tion. Bending and Ring Making. Miscellaneous Examples of Forged Work. 
Cranks, Model Work, and Die Forging. Home-made Forges. The Manipula- 
tion of Steel at the Forge. (Continued on next page.) 

DAVID McKAY, Publisher, 1022 Market Street, Philadelphia. 



HANDICRAFT SERIES {continued). 

Glass Working by Heat and Abrasion. With 300 Engravings 
and Diagrams. 

Contents. — Appliances used in Glass Blowing. Manipulating Glass Tubing. 
Blowing Bulbs and Flasks. Jointing Tubes to Bulbs forming Thistle Funnels, 
etc. Blowing and Etching Glass Fancy Articles ; Embossing and Gilding Flat 
Surfaces. Utilising Broken Glass Apparatus ; Boring Holes in, and Riveting 
Glass. Hand-working of Telescope Specula. Turning, Chipping, and Grinding 
Glass. The Manufacture of Glass. 
Building: Model Boats. With 168 Engravings and Diagrams. 

Contents.— '^KViX^xaZ Model Yachts. Rigging and Sailing Model Yachts. 
Making and Fitting Simple Model Boats. Building a Model Atlantic Liner. 
Vertical Engine for a Model Launch. Model Launch Engine with Reversing 
Gear, Making a Show Case for a Model Boat. 
Electric Bells, How to Make and Fit Them. With 162 En- 

graving s and Diagrams. 

Contents. — The Electr c Current and the Laws that Govern it. Current 
Conductors used in Electric-Bell Work. Wiring for Electric Bells. Elaborated 
Systems of Wiring ; Burglar Alarms. Batteries for Electric Bells. The Con- 
struction of Electric Bells, Pushes, and Switches. Indicators for Electric-Bell 
Systems. 
Bamboo Work. With 177 Engravings and Diagrams. 

Contents. — Bamboo ; Its Sources and Uses. How to Work Bamboo. Bamboo 
Tables. Bamboo Chairs and Seats. Bamboo Bedroom Furniture. Bamboo 
Hall Racks and Stands. Bamboo Music Racks. Bamboo Cabinets and Book- 
cases. Bamboo Window Blinds. Miscellaneous Articles of Bamboo. Bamboo 
Mail Cart. 
Taxidermy. With 108 Engravings and Diagrams. 

Contents. — 'SiV\x\vi\v\'g Birds. St.ffmg and Mounting Birds. Skinning and 
Stuffing Mammals. Mounting Animals' Horned Heads : Polishing and Mount- 
ing Horns. Skinning, Stuffing, and Casting Fish. Preserving, Cleaning, and 
Dyeing Skins. Preserving Insects, and Birds' Eggs. Cases for Mounting 
Specimens. 
Tailoring;. With 180 Engravings and Diagrams. 

Contents. — Tailors' Requisites and Methods of Stitching. Simple Repairs 
and Pressing. Relining, Repocketing, and Recoliaring. How to Cut and 
Make Trousers. How to Cut and Make Vests. Cutting and Making Lounge 
and Reefer Jackets. Cutting and Making Morning and Frock Coats. 
Photographic Cameras and Accessories. Comprising How to 
Make Cameras, Dark Sliles, Shutters, and Stands. With 160 
Illustrations. 

Contents. — Photographic Lenses and How to Test them. Modern Half-plate 
Cameras. Hand and Pocket Cameras. Ferrotype Cameras. Stereoscopic 
Cameras. Enlarging Cameras. Dark Slides. Cinematograph Management. 

Optical Lanterns. Comprising The Construction and Management 
OF Optical Lanterns and the Making of Slides. With 160 
Illustrations. 

Contents. — Single Lanterns. Dissolving View lanterns. lUuminant for 
Optical Lanterns. Optical Lantern Accessories. Conducting a Limelight 
Lantern Exhibition. Experiments with Optical Lanterns. Painting Lantern 
Slides. Photographic Lantern Slides. Mechanical Lantern Slides. Cinemato- 
graph Management. 
Engraving Metals. With Numerous Illustrations. 

Contents. — Introduction and Terms used. Engravers' Tools and their Uses, 
Elementary Exercises in Engraving. Engraving Plate and Precious Metals, 
Engraving Monograms, Transfer Processes of Engraving Metals, Engraving 
Name Plates. Engraving Coffin Plates. Engraving Steel Plates. Chasing 
and Embossing Metals. Etching Metals. 

Basket Work. With 189 Illustrations, 

Contents. — Tools and Materials. Simple Baskets. Grocer's Square Baskets. 
Round Baskets, Oval Baskets, Flat Fruit Baskets, Wicker Elbow Chairs. 
Basket Bottle-casings. Doctors' and Chemists' Baskets. Fancy Basket Work. 
Sussex Trug Basket. Miscellaneous Basket Work. Index 

DAVID McKAY, Publisher, 1022 Market Street, Philadelphia. 



HANDICRAFT SERIES {continued). 

Bookbinding. With 125 Engravings and Diagrams. 

Contents. — Bookbinders' Appliances. Folding Printed Book Sheets. Beat- 
ing and Sewing. Rounding, Backing, and Cover Cutting. Cutting Book Edges, 
Covering Books. Cloth-bound Books, Pamphlets, etc. Account Books, 
Ledgers, etc. Coloring, Sprinkling, and Marbling Book Edges. Marbling 
Book Papers. Gilding Book Edges. Sprinkling and Tree Marbhng Book 
Covers. Lettering, Gilding, and Finishing Book Covers. Index. 

Bent Iron ^A/ork. including Elementary Art Metal Work. With 
269 Engravings and Diagrams. 
Contents. — Tools and Materials. Bending and Working Strip Iron. Simple 
Exercises in Bent Iron. Floral Ornaments for Bent Iron Work. Candlesticks. 
Hall Lanterns. Screens, Grilles, etc. Table Lamps. Suspended Lamps and 
Flower Bowls. Photograph Frames. Newspaper Rack. Floor Lamps. 
Miscellaneous Examples. Index. 

Photography. With 70 Engravings and Diagrams. 

Contents. — The Camera and its Accessories. The Studio and Darkroom. 
Plates. Exposure. Developing and Fixing Negatives. Intensification and 
Reduction of Negatives. Portraiture and Picture Composition. Flashlight 
Photography. Retouching Negatives. Processes of Printing from Negatives. 
Mounting and Finishing Prints. Copying and Enlarging. Stereoscopic 
Photography. Ferrotype Photography. Index. 
Upholstery. With 162 Engravings and Diagrams. 

Cotttents. — -Upholsterers' Materials. Upholsterers' Tools and Appliances. 
Webbing, Springing, Stuffing, and Tufting. Making Seat Cushions and Squabs. 
Upholstering an Easy Chair. Upholstering Couches and Sofas. Upholstering 
Footstools, Fenderettes, etc. Miscellaneous Upholstery. Mattress Making 
and Repairing. Fancy Upholstery. Renovating and Repairing Upholstered 
Furniture. Planning and Laying Carpets and Linoleum. Index. 

Leather Working. With 152 Engravings and Diagrams. 

Contents. — Qualities and Varieties of Leather. Strap Cutting and Making. 
Letter Cases and Writing Pads. Hair Brush and Collar Cases. Hat Cases. 
Banjo and Mandoline Cases. Bags. Portmanteaux and Travelling Trunks. 
Knapsacks and Satchels. Leather Ornamentation. Footballs. Dyeing 
Leather. Miscellaneous Examples of Leather Work. Index. 

Harness Making. With 197 Engravings and Diagrams. 

Contents. — Harness Makers' Tools. Harness Makers' Materials. Simple 
Exercises in Stitching. Looping. Cart Harness. Cart Collars. Cart Saddles. 
Fore Gear and Leader Harness. Plough Harness. Bits, Spurs, Stirrups, and 
Harness Furniture. Van and Cab Harness. Index. 

Saddlery. With 99 Engravings and Diagrams. 

Contents. — Gentleman's Riding Saddle. Panel for Gentleman's Saddle. 
Ladies' Side Saddles. Children's Saddles or Pilches. Saddle Cruppers, Breast- 
plates, and other Accessories. Riding Bridles. Breaking-down Tackle. Head 
Collars. Horse Clothing. Knee-caps and Miscellaneous Articles. Repairing 
Harness and Saddlery. Re-lining Collars and Saddles. Riding and Driving 
Whips. Superior Set of Gig Harness. Index. 

Other Volumes in Preparation. 



DAVID McKAY, Publisher, 1022 Market Street, Philadelphi; 



WORK'' HANDBOOKS 



ELECTRO-PLATING 



ELECT RO-PLATIMI 



WITH NUMEROUS ENGEAVINGS AND DIAGRAMS 



EDITED BY 

PAUL N. HASLUCK 

EDITOR OF "work" AND "BUILDING WORLD" 
AUTHOR OF " HANDYBOOES FOR HANDICRAFTS," ETC. ETC. 



PHILADELPHIA 

DAVID McKAY, Publisher 

()10, SOUTH WASHINGTON SQUARE 



1905 



'f -• 



\\z^ 



K 



o ") 



y}'^C^' 



5 2^ 



Q PREFACE. 

I This Handbook contains, in a form convenient for 
everyday use, a comprehensive digest of the informa- 
tioQ on Electro-plating, scattered over more than twenty 
thousand columns of Work— one of the weekly 
journals it is my fortune to edit — and supplies concise 
information on the details of the subjects on which 
it treats. 

In preparing for publication in book form the mass 
of relevant matter contained in the volumes of Work, 
much had to be arranged anew. However, it may be 
mentioned that a number of articles by Mr. G. E. 
Bonney have been incorporated in the text. 

Readers who may desire additional information 
respecting special details of the matters dealt with in 
this Handbook, or instructions on kindred subjects, 
should address a question to Work, so that it may 
be answered in the columns of that journal. 



P. N. HASLUCK. 



La Belle Sauvage, London. 
Fehniary, 1905. 



CONTENTS, 



I.— Introduction : Tanks, Vat.'^, and other Ap 
paratus 

II.— Batteries, D3^namos, and Electrical Acces 
soriei ..... 



in.— Appliances for Preparing and Fini 
Work 

IV.— Silver plating 

v. — Copper-plating .... 

YL— Gold-plating 

VII. — Nickel-plating and Cycle-])lating 

VIII.— Finishing Electro-plated Goods . 

IX. — Electro-plating ^Yith Various Metals 
Alloys 

Index 



shing 



and 



24 

5G 
71 



90 
101 
125 

145 

154 
158 



LIST OF ILLUSTRATIONS. 



FIG. PAGE 

1.— Diagram showing Positions of Anode and Catiiode in 

Electro-plating 11 

2.— Scouring Trough 16 

3— Plating Vat 17 

4.— Iron Stand for Vat 19 

5.— Copper Hook . . . 19 

6.— Steam-heated Sawdust Pan 21 

7.— Roseleur's Plating Balance 22 

8.— Daniell Cell 27 

9.— Bun sen Battery 27 

10.— Wollaston Battery 31 

11.— Part of Battery Plate Support 33 

12.— Battery Plates Mounted for Use 33 

13.— Smee Cell 34 

14,— Battery of Smee Cells 35 

15.— Fuller Cell 37 

16.— Gassner Dry Cell 39 

17.— Leclanche Cell 39 

18.— Electro-plater's Dynamo 45 

19.— Semi-enclosed Plating ' Dynamo 4? 

20.— Conducting and Supporting Rod 51 

21.— Resistance 53 

22.— Resistance Bo^d, combined with Ammeter . . . 53 

23.— Ammeter showing Rate of Deposit 55 

24.— Diagram of Electrical Connections 55 

25.— Treadle Polishing Machine 57 

26.— Bench Polishing Machine 57 

27.— Power-driven Polishing Machine 58 

28, 29.— Spindles for Mops and Dollies 58 

30.— Combined Treadle Scratch Brush and Polishing Lathe 59 

31. 32, 33.— Leather-covered Bobs 61 

34.— ^Sections of Bobs 65 

35.— Emery Tape Machine 65 

36.— Buff Stick 65 

37.— Calico Mop 65 

38.— Woollen Brush 66 



8 Electro-PL A ting. 

i'lG. PAGE 

39.— Section of Circular Brush 67 

40, 41.— Scouring Brushes 67 

42, 43.— Potash Brushes 68 

44.— Scratch-knot 68 

45, 46.— Hand Scratch-brushes 68 

47.— Brass Wire Brush 69 

48.— Crimped Wire Cup Brush 69 

49.— Turk's Head Cup Brush 69 

50.— End Brush 69 

51, 52.— Watch-case Brush 69 

53.— Inside Thimble Brush 69 

54.— Inside Box Brush 69 

55.— Inside Ring Brush 69 

56.— Bottom Brush 69 

57— Scratch Knot Lathe 70 

58, 59, 60.— Dipping Baskets 75 

61.— Small Gilding Outfit 103 

62.— Improved Hook for Nickel Anode 130 

63.— Straight Burnisher 149 

64.— Curved Burnisher 149 

65.- Curved Burnisher 149 

66.— Curved Burnisher 149 

67.— Round Burnisher 149 

63.— Hooked Burnisher 150 

69.— Curved Burnisher 150 

70.— Burnisher for Corners 150 

71.— Hooked Buruislier 150 

72.— Pointed Burnisher 150 

73.— Agate Burnisher . . .151 

74.— Agate Burnisher 151 

75.— Agate Burnisher 151 

76.— Agate Burnisher 151 

77.— Buff for Polishing Burnishers I53 



BLBCTRO-PLATING. 



CHAPTER I. 

introduction: tanks, vats, and other 
apparatus. 

Electro-plating is the process by which a metal 
or alloy held in solution by a liquid is deposited 
electrically on a prepared surface. From the solu- 
tion, the metal (nickel, silver, brass, copper, etc.) 
is thrown on to the object receiving the deposit, 
and simultaneously an equal quantity of a similar 
metal to that held in solution is fretted off from 
metal plates (anodes) suspended in the electro- 
plating bath. Thus, although the solution is being 
constantly robbed of metal, it is yet being fed, 
and so its strength is maintained. Of course, the 
anodes must be plates of similar rhetal to that 
contained in solution ; thus, nickel anodes in a 
nickel solution, silver anodes in a silver solution, 
and so on. 

Anode is the name given by Dr. Faraday to the 
positive plate or wire in a solution undergoing 
electrolysis. It is derived from two Greek words : 
ana, meaning "upwards"; and odos, "a way'' — 
the way in whicli the sun rises — and is an indica- 
tion that the current rises from the battery to enter 
the electro-plating solution, this way being from 
the negative element of the battery to the positive 
element in the solution to be electrolysed (see the 
arrows in Fig. 1). The negative element of a 
battery receives the electric current immediately 
it is generated, and transmits it to the anode 



T o Electro-pla riNG. 

placed in the electro-plating bath ; the negative 
element is, therefore, the positive pole, and its 
connection to the anode by a wire makes the anode 
the positive pole or element in the solution. By 
way of illustration : the carbon element in a Bun- 
sen battery (see pp. 28 to 30) is the negative 
element, because it receives the electric current 
generated by the positive, or zinc, element of the 
battery ; but it is also the positive pole, because, 
through it and its metal connections, the current 
is transmitted to work outside the battery. Fig. 1 
shows at a glance what is meant. 

Another scientific term has now to be referred 
to. Anion is a term invented by Dr. Faraday to 
indicate the radical of an acid, or the portion of a 
salt set free at the anode during electrolysis. It 
has been defined as " the electro-negative, or chlo- 
rous radical of the acid or salt decomposed." 
Assume that a solution of the double cyanide of 
silver and potassium is being used in the work of 
electro-plating. The salt of silver in this solution 
is combined with a salt of potassium, and three 
distinct substances are present, apart from the 
water which holds them all in solution ; these are 
—silver, potassium, and cyanogen. When the 
electric current is passing through the solution 
in the process of plating, silver and potassium are 
set free at the goods being plated, and cyanogen 
is set free at the silver anode. The salt is thus 
broken up or decomposed, and cyanogen is the 
anion of this salt. 

Anodes may be soluble or insoluble in an 
electrolyte, as may be required to suit the nature 
of the work in hand. Insoluble anodes are used 
when it is wished to decompose an electrolyte, 
and break it up into its several component parts 
without adding another element to it, as when 
acidulated water is decomposed by the electric 
current to form oxygen and hydrogen — in which 
case a platinum anode is used, because platinum 



Tanks, Vats, and other Apparatus. ii 

is not soluble in the acidulated solution. Insolu- 
ble anodes are also used when it is wished to 
extract all the metal from its solution, and deposit 
it in a pure condition on the cathode (the article 
plated). Anodes are said to be insoluble when 
they are made of elements which are neither 
soluble in the solution to be electrolysed, nor can 
be made soluble therein under the influence of the 
electric current. Some solutions of the acids and 
alkalis will act very feebly, or not at all, on an 
element, even when heated to boiling point, but 



ANOC 



CATHODE 




1. — Diag-ram showino- Positions of Anode and 
Cathode in Electro-plating-, 



will dissolve it freely when a current of electricity 
is passed from it through the intractable solutions. 
For instance, gold is only feebly soluble in a strong 
solution of potassium cyanide when exposed to 
air, even when the solution is heated ; but it is 
freely soluble in the same solution when only a 
feeble current of electricity is passed from it 
through the solution. Insoluble anodes are 
generally made of platinum or carbon. 

Soluble anodes are used when it is wished to 
maintain an electrolyte (the plating solution) at its 



1 2 Electro-pla ting, 

original strength— that is, to contain the same 
quantity of metal in the solution after it has been 
worked as it had when first made up. To do this, 
the anode must be only soluble in the solution 
whilst the current is passing, and then only to an 
extent equal to the rate of metal deposited. Un- 
less an equivalent of metal is dissolved from the 
anode for each equivalent of metal deposited at 
the cathode, the original composition of the solu- 
tion cannot be maintained during the process of 
electrolysis or plating. 

The cathode is the opposite of the anode, the 
term being derived from the Greek fcafa, meaning 
" down,'^ and odos, "a way'." Thus the word sig- 
nifies that the current passes down to it from the 
anode ; the current returns to the negative pole 
of the battery attached to the positive plate, thus 
completing the electrical circuit. The object being 
plated forms the cathode ; and just as the anode 
is connected electrically to the battery's positive 
pole, BO is the cathode connected to the negative 
pole. 

For the present, this is all the theory of the 
process of electrolysis that it is desirable to 
explain, further information being given as the 
practice of electro-plating is dwelt upon. It must 
not be inferred from the theoretic explanation 
just given that electro-plating consists merely in 
taking any metal article, making the necessary 
connections, immersing the article in the solution, 
and then taking it out bright with its new coat of 
deposited metal. There is much to be understood 
before successful plating can be accomplished ; 
the appliances necessary for work on a big scale 
are many and expensive ; and the manipulation of 
the various metals calls for a special knowledge 
of the characteristics of each one. This hand- 
book will deal with many matters of importance 
to the electro-plater, and will discuss, in the order 
in which the items are here mentioned, the electro- 



Tanks, Vats, and other Apparatus. 13 

plater's shop, tanks, vats, and other general 
requisites ; batteries, dynamos, and electrical ac- 
cessories ; the appliances for preparing the rough 
metal surfaces to receive the electro-deposited 
coat, and for polishing the plated ware ; the 
proper materials, appliances, and methods em- 
ployed in electro-plating with silver, copper, gold, 
nickel, iron, lead, tin, platinum, and alloys, and the 
methods of finishing plated goods. 

Persons desiring a small plating plant for the 
purpose of treating trinkets, miscellaneous small 
articles of the nature of spoons, forks, etc., need 
not be deterred from carrying out their wishes by 
the magnitude of the operations or by the expense 
of the apparatus described in this and succeed- 
ing chapters. Metal can be polished by hand to 
look almost as ))right as machine-polished metal, 
using the same polishing materials and suitable 
brushes. Small quantities of the same solutions 
can also be used in smaller vessels, and gold, 
silver, etc., can be deposited in good condition 
with current obtained from small cells. It must 
be understood, however, that the same strict 
attention to absolute cleanliness, and care in 
preparation, must be observed in small operations, 
and the same rules must guide the worker when 
plating a spoon or a screw as when plating the 
handle-bar of a bicycle. Readers will find that 
special attention is paid to the requirements of the 
amateur and small professional plater in later 
chapters, their limitations having been taken into 
careful consideration. 

The plating shop must be well lighted and 
ventilated, and kept at a temperature of about 
60° F. Good light, preferably from high windows 
or from a skylight, is necessary for the examina- 
tion of the work ; but receptacles containing silver 
solutions should be protected from the action of 
direct sunlight. Good light is required over the 
scouring trough and vats, to enable the workmen 



14 Electro-PL ATI XG. 

to note changes of colour in the metals ; but the 
light over the vats should be a northern light if 
possible, because sunlight decomposes all plating 
solutions. The plating shop should be roomy and 
clean, for the most perfect cleanliness in the pro- 
cess is necessary to success. The plating vats should 
be covered with canvas when not in use, to exclude 
dust. Ventilation is necessary, because all the 
exhalations of gas from the solutions are extremely 
poisonous and soon debilitate the strongest work- 
men when fresh air is absent. Not only is an 
even temperature conducive to regular working of 
the solutions, but the employes do better and more 
work when the shop is well ventilated and comfort- 
ably warmed. 

If the solution vats are placed in a corner of 
an ordinary workshop, they will soon get con- 
taminated with dust and dirt. If the dynamo is 
near the polishing lathe, or where metal dust is 
flying about, it will soon be ruined. 

Metal castings, forgings, etc., are surfaced for 
plating on emery bobs, etc., as will be described 
in later chapters ; they are then immersed in a 
hot solution of caustic potash, to loosen and re- 
move grease and oil contracted at the polishing 
lathe. The solution for this purpose is contained in 
a wrought-iron tank, the usual dimensions for which 
are 4 ft. by 2 ft. by 1 ft. 9 in., to hold 50 gallons 
of liquid ; or one for larger work, measuring 5 ft. 
by 2 ft., to hold 100 gallons. The size of the tank 
will be determined by that of the work, and the 
vessel must be large enough to receive the longest 
articles likely to be plated. It is made of wrought 
iron, which is not attacked by caustic potash. 
Tanks of galvanised iron, lead-lined tanks, zinc 
tanks, and tanks with soldered joints are unsuit- 
able, because all these metals and solder are 
soluble in caustic potash, which will hold the dis- 
solved metal in solution and deposit it on any 
articles cleaned in the tank. 



Tanks, Vats, a.yd other Apparatus. 15 

As the potash sohition will have to be worked 
hot, the tank must be placed in a position where 
ifc can be conveniently heated, either by steam 
passing through a coil of iron pipe in the solution, 
hy an ordinary furnace in which coal or coke is 
burnt, or by gas jets. Steam and gas are prefer- 
able to coal, because the heat can be regulated 
to a nicety, and there is no danger from fire after 
the day's work is done. Even when heated by 
steam, it is advisable to support the tank above 
the floor on brickwork to a height suitable for 
easy working. The solution is composed of 
American potash dissolved in water, at the 
strength of 1 lb. to each gallon of water. 

The articles are rinsed in hot water after they 
are taken from the potash tank, so a second tank, 
of equal dimensions and of the same material, 
must be fitted up in a similar manner next to the 
potash tank. This is kept supplied with clean hot 
water. 

In the preparatioii of articles to be plated, the 
polisher aims at getting the finest polish obtain- 
able on the surface of the article ; whilst the plater 
tries to free the surface from every trace of grease, 
oil, sweat, and other foreign matter. The polished 
work may be beautifully clean from a polisher's 
point of view, and yet be very dirty when viewed 
from the plater's point of view. The surface musi 
be chemically clean before the article is placed 
in the plating vat, to ensure the deposited coat oE 
metal adhering firmly to the surface of the metal 
on which it is deposited. The vessel in which the 
articles are thus further cleansed is named the 
scouring trough or tray, and is show^n by Fig. 2. 
It consists, as shown, of a shallow trough of thick 
wood divided into two parts, lined with lead, and 
furnished at one end with a plug and overflow 
pipe. In some scouring trays a narrow shelf is 
fixed a little below the upper edge, and the work 
rests on this whilst being cleaned. Some work- 



1 6 Electro-pla ting, 

men hold the work on a piece of board placed 
across the tray. The tray must be placed on 
strong wooden trestles, at a height to suit the 
workman, and kept half full of clean water, to 
rinse the articles after scouring. 

The plating vat is the name given to the vessel 
intended to hold the plating solutions. This vessel 
must be roomy enough to take the largest article 
likely to be plated in it, and then leave an 
abundance of space all round. It is usual to plan 
plating vats to hold several such articles at 



Fig. 2. — Scouring Trough. 

once, so that time may be saved. Those in 
general use for nickel, copper, brass, and silver- 
plating, are made of thick pine-wood, well jointed, 
and strengthened with iron bolts across the ends, 
lined with sheet-lead put together with burnt 
joints, then match-lined to prevent metallic con- 
tact with the lead lining. The appearance of these 
vessels when finished is shown by Fig. 3. They 
are made in a great number of sizes, the capacities 
ranging from 19 gal. to several hundred gallons. 

A vat to hold the solution may be of vitreous 
stoneware ; but this material is liable to fracture. 



Tanks, Fats, and other Apparatus. 



A7 



and is not easily made into large rectangular 
vessels. The next best is enamelled iron, which, 
being smooth, retards the creeping action of the 
cyanide salts, so that the sides of the vat are kept 
clean, and enamelled iron vats are suitable for small 
work ; their use is almost compulsory when the 
solution must be used hot. In large plating 
establishments the vats are wood, lined with 
lead, as already mentioned. 

Plating vats constructed of thick slate slabs, 
grooved and well bolted together, are also sold 
for the purpose, but apparently they cost 50 per 




Fiof. 3.— Platino- Yat. 



cent, more than the lead-lined wood vats. Vats 
made of iron only, unless they are lined with 
thick enamel, are altogether unsuitable as plating 
vats ; copper, brass, iron, and zinc are readily 
corroded by the action of the acid or the alkali 
present in the plating solution. 

A light vat should be supported on short stout 
trestles, at a height suitable to the workmen — that 
is, with the upper rim about the same height as 



an ordinary table. 

B 



Two, three, or four such 



I 8 El EC TR O-PLA TING, 

supports will be required, according to the length 
of the vat. If, however, the vat is large and 
heavy, it should be supported by a strong founda- 
tion of masonry, and this should be so built as to 
ensure free access of air to the under side, thus 
preventing rot in the wood. If the floor round 
the vat can be coated with cement or asphalt it 
can be easily kept clean, and it is also advisable 
to have w^ooden grids on the floor by the sides of 
the vat, on which the workmen may stand. 

Special iron stands for vats can be obtained 
(see Fig. 4) ; these are provided with means of 
heating the vat by gas. 

It is possible to make a small electro-plating 
bath with glass plates cemented together and en- 
closed in a wooden box. The cement may be 
either marine glue, which can be bought, or 2 parts 
of pitch and 1 part of gutta percha can be melted 
together. Pour some of the melted material into 
the wooden box and spread in a thin layer over 
the bottom with a warm iron ; while the cement 
i3 warm (not hot) press the bottom plate firmly 
into it. The sides may be treated in the same 
way, but before putting in the glass plates warm 
them gently and coat all the edges with a thin 
layer of the cement, so that when they are pressed 
together the surfaces will adhere thoroughly ; the 
joints will then be waterproof. Make the wood 
box a trifle large, allowing room for the layer of 
cement, or if the glass plates be forced in and 
nothing allowed for contraction and expansion the 
glass box will probably crack at the weakest part. 
Another suitable cement is prepared as follows : 
Make some good flour paste, and allow^ to get cold. 
Prepare a quantity of thin glue, add 10 gr. of 
powdered bichromate of potash to each gill of 
glue, bring it to a boiling temperature, and then 
pour it into the cold paste w^iilst stirring. Use 
this cement warm, and expose to strong sunlight 
afterwards. It will resist acids, but not hot 



Tanks, Vats, axd other Apparatus. 



19 



cyanide of potassium solutions. Still another 
cement is made by dissolving best isinglass in 
acetic acid by the aid of heat ; it is used hot. 

The electrical fittings of the plating vat are 
described in the next chapter. 

The articles to be plated are suspended in the 
plating solution from copper rods (see p. 51) by 
means of short lengths of wire, named slinging 
wires. These are made of bare copper wires, 
ranging in gauge from No. 8 to No. 18, the larger 




Fig. 4. — Iron Stand for Vat. Fig-. 5. — Copper Hook. 

size being employed for heavy, and the smaller 
sizes for light, articles. Two wires of No. 18 will 
hold up a cycle handle-bar ; but it is always ad- 
visable to have more wires or larger wires than 
required merely to support the articles, since these 
wires convey the electric current from the goods 
being plated ; and an insufficient wire conductor 
here w^ill prevent the nickel from going on as fast 
or as well as may be required. Small wires offer 
a greater resistance to the current, and should be 
avoided for this reason. 

The connection between the slinging wires and 
the articles to be plated is by means of copper 



20 Electro-plating. 

hooks, the usual pattern of which is shown by 
Fig. 5. 

The plated articles are rinsed in hot water 
after leaving the plating vat, and are then trans- 
ferred at once to hot boxwood sawdust, in which 
they are dried quickly. This treatment is needed 
to prevent the coat of deposited metal from being 
marked by stains. The sawdust is held in a 
shallow pan or tank of iron placed next the hot 
water tank. This pan is heated by hot water or 
steam. If hot water is used, it occupies the double 
bottom, this being heated by steam jets ; by 
the other method, the steam passes through a 
coiled pipe in the double bottom (see Fig. 6). 
Direct heat from a fire or from gas jets is in- 
admissible, because this would char the sawdust, 
and thus stain the work. If live high-pressure 
steam is employed, this should be used in a coil 
of pipes not directly in contact with the sawdust 
(see Fig. 6), as such very hot steam is liable to 
char the sawdust. Boxwood sawdust is employed, 
because this does not contain resinous matter, 
likely to be extracted by heat, and etain the 
metal ; but the sawdust of sycamore could be used 
as a substitute if more readily obtainable. The 
sawdust tank and the hot-water tank may be of 
galvanised iron, if this is of any advantage. 

The Bunsen burner will frequently be useful. 
It is composed of a short burner inside a piece 
of gas barrel some five or six inches in length, 
to which air is admitted at the lower end. 
The air mixes with the incoming gas in the 
barrel, and the mixture burns together at the 
top with an intensely hot, smokeless, and non- 
luminous flame. When the tube of the burner is 
surmounted with a cap, the flame spurts out of 
the holes, and forms a " rose burner," the flame 
from which can be used for general heating 
purposes. 
- The balances or scales required by an electro- 



Tanks^ Fats, and other Apparatus. 21 

plater will vary with the class of work on which 
he is engaged. For the ordinary work of weigh- 
ing the goods before and after plating, to deter- 
mine how much metal has been deposited, a pair 
of scales with a stout steel or brass beam will 
be required. For weighing gold and gilded 
articles a lighter pair, indicating a turn on one 
grain at least, should be provided ; these will also 
serve for weighing out the ingredients used in 
making up solutions. For rough assays and esti- 
mations a small cheap balance indicating a turn 




Fig-. G. —Steam-heated iSawdust Pan. 

of i\) grain will serve the purpose ; the cost of 
this, together with weights from 500 grs. down 
to y^Q grain, will be about £l 10s. For assays, 
analysis, and calibrations, a still more elaborate 
and delicate balance will be required, such as an 
Oertling assay balance fitted with agate bearings 
and indicating a turn with at least y^oth of a 
grain. Such a balance, with a full set of weights, 
will cost from £5 to £lO. 

In some plating establishments the weight of 
deposited metal is determined during the opera- 
tion of plating by means of a plating balance. 
This is merely a pair of large scales furnished 
with a scale pan at one end of the beam and a 



2 2 Electro-PL A ting. 

metal frame suspended over the bath at the other 
end. The goods to be plated are slung to the 
metal frame, and the whole is balanced by weights 
placed in the scale pan. The pillar of the beam 
is connected to the negative pole of the machine 
or battery. As the metal goes on th-^ goods to 




7. — Roseleur's Plating- Balance. 



be plated, the beam is thrown out of balance, 
and the exact weight deposited can be ascer- 
tained at any time by additional weights placed 
in the scale pan. 

Roseleur's plating balance is shown by Fig. 7. 
Tlie beam carries at one end a metal ring e, from 
which the objects to be plated are suspended in 



Tanks, Vats, and other Apparatus. 23 

tlie bath B. The anode a is shown as a rod con- 
nected through terminals, etc., to the positive pole 
of the battery. From the opposite end of the 
balance the pan s is hung. A metal pin m dips 
into the mercury cup n, and this cup is connected 
to the negative pole of the battery. The path of 
the current is therefore from the battery by way 
of the anode a through the bath, and thence, by 
way of the articles to be plated, through the beam 
and mercury contact back to the battery. In the 
horizontal position of the beam, m does not make 
contact with /(. But the weight of the articles is 
balanced by adding weights to the pan s, and 
further weights are then added equal to the 
weight of silver to be deposited. This brings m 
down and completes the circuit. When the re- 
quired w^eight of metal has been deposited, the 
left arm of the beam (as seen in Fig. 15) rises 
and breaks the circuit. It will be seen that the 
balance is automatic, cutting off the current when 
the articles are plated to the extent intended. 

The work of the plating balance is done in a 
different way by a special ammeter (p. 54) which 
records the amount of silver deposited per hour. 

Beakers are tumblers made of very thin 
Bohemian glass for special use in chemical 
manipulations where small quantities of acids and 
other liquids are employed at high temperatures. 
Tumblers made of ordinary glass would soon 
break in pieces, but these thin glass beakers will 
bear boiling water being poured into them, or 
will hold acid whilst it is being boiled in them 
over a gas stove. They are also useful in analysis 
of solutions, as the clear glass enables the opera- 
tion of precipitation to be observed whilst the 
operator holds the beaker away from his face, and 
thus avoids breathing the deleterious fumes. 



24 



CHAPTER II. 

BATTERIES, DYNAMOS, AND ELECTRICAL 
ACCESSORIES. 

The electric current used to deposit metal from 
plating solutions must be obtained from a con- 
venient source ; this may be a battery for occa- 
sional jobs, and for the general use of the amateur 
or small professional ; and it may be a dynamo 
when large quantities of work have to be treated. 
The advantages of the dynamo are many. The 
current is more constant, labour is lessened, and 
the cost of maintenance is much reduced. The 
current can also be regulated, and thus any class 
of work can be done from one machine. A plating 
dynamo gives a large current at a low pressure ; 
the armature may be of the drum or ring pattern, 
and the machine is shunt wound. With a large 
machine, capable of giving, say, 200 amperes, 
large surfaces of work may be acted on in several 
vats simultaneously, and nickel-plating may pro- 
ceed at the same time as silver-plating. 

The electro-motive force required to be sup- 
plied by the battery or dynamo varies according 
to the bath. Thus, f<>r gold and silver, it may be 
from ^ to 4 volts ; for copper, with an acid bath, 
it may be from ^ to 1^ volts, or, with a cyanide 
bath, from 3 to 6 volts. The amperage will vary 
with the area of the anode and cathode surfaces. 

The word battery, as applied to electrical ap- 
paratus, belongs strictly to a collection of Leyden 
jars charged with static electricity. These dis- 
charge their store of force in a violent manner, 
totally unlike the equable flow of current obtained 
from collections of voltaic or galvanic cells. 



Batteries, Dynamos, and Accessories. 25 





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2 6 Electro-pla ting. 

French electricians speak and write of such 
generators under the name of "Piles/' doubtless 
in deference to the form of the first voltaic 
generator of electricity made — the pile of metal 
discs invented by Yolta. English electricians 
apply the word battery to all apparatus in which 
electricity is generated by chemical decomposi- 
tion, and also to tAvo forms of storage cells 
known respectively as accumulators and Leyden 
jars. 

A tabulated list of the batteries in use by 
electro-platers is given on p. 25, and the table 
will show at a glance the battery most suitable for 
any particular work. 

Other batteries, such as the Fuller, Wollaston, 
Gassner, and very occasionally the Leclanche, are 
also used by some platers ; these will be referred 
to later. 

The Daniell is best for depositing copper from 
its sulphate solution and silver from the usual 
plating solution, but the Bunsen may be used for 
this purpose if the exciting liquid is sufficiently 
weakened. One or two large cells in series will 
be enough for all ordinary purposes. The Bunsen 
is best for depositing copper and brass from their 
alkaline solutions, and also for the deposition of 
nickel, because its electro-motive force is high, 
enabling the current to push through high resist- 
ances. It is not suitable for the work of silver- 
plating, gilding, and electrotyping, because its high 
E.M.F. causes the metal to go on too fast and in a 
granular condition. In all these operations the 
Daniell will be found to be the best because its 
E.M.F. is lower than that of the Bunsen, and its 
current equally constant in volume. The Smee, 
and also Walker, are eminently useful cells for 
giving a current suitable to the w^ork of electro- 
gilding small articles of jewellery. Batteries with 
a high E.M.F. cause gold to go on too fast, and 
give the deposit a brown colour. 



Batteries^ Dynamos, and Accessories. 27 

Some information as to the form and construc- 
tion of the various batteries used by electro- 
platers may now be given. 

The Daniell cell is known in several modifica- 
tions, Fig. 8 showing the internal arrangement 
of the porous pot form. The glass or glazed 
vitrified stoneware jar J contains the cylindrical 
plate c (made of sheet copper), the porous pot p 
(made of uri glazed earthenware), and the zinc 




Bunsen Battery. 



rod z. Inside the porous pot dilute sulphuric 
acid is poured, while the copper plate c stands in 
a saturated solution of copper sulphate. The 
connections are made to the two wires shown in 
the illustration. The maximum electromotive 
force of the cell is about 1-14 volts, with an 
internal resistance of 3 ohms in the 3-pint size, 
and 1'6 ohms in the 3-quart size. 

A Daniell battery is re-charged in the following 
way: Thoroughly clean all the parts and reamal- 



2 8 Electro-pla ting. 

gamate the zincs ; charge the porous pot, contain- 
ing the zinc, with a solution of 1 part of sulphuric 
acid in 12 or 13 parts of water, and the outer 
jar, containing the copper plate, with a saturated 
solution of sulphate of copper. The small sieve 
or tray near the top of the containing jar, but 
below the level of the copper solution, should 
contain crystals of sulphate of copper to keep the 
solution saturated. If copper is allowed to de- 
posit on the porous pot, the current will fail, not 
only on account of a higher internal resistance, 
but also because this short-circuits the cells. To 
prevent this, the zinc and also the zinc sediment 
must be kept from touching the porous partitions. 

The Daniell battery is very constant. Whilst 
the sulphate of copper solution is kept saturated, 
and the zinc kept in working order (well amalga- 
mated — coated with mercury), the current will not 
flag at all during the day ; it is therefore most 
suitable for silver-plating and gilding, but it is 
very troublesome to keep in working order, unless 
kept well at work and employed every day. 

The Bunsen battery as used in England is 
made up of an outer containing cell of stoneware, 
containing a cylinder of amalgamated zinc, inside 
which is a cell of porous earthenware containing 
a square bar of carbon (see Fig. 9). The outer 
cell is charged with sulphuric acid diluted with 
water, and the inner cell is charged with strong 
commercial nitric acid. The electro-motive force 
given by this cell is variously stated by authorities 
as r85 to 1"95 volts. The internal resistance of 
the cells varies with their size, the condition of 
the porous cell, and the condition of the acid 
charges ; the resistance being variously given as 
0-30, 0-08, and 0*06 ohms These probably repre- 
sent respectively the pint, quart, and half-gallon 
sizes of cells used by the persons testing them. 
The E.M.F. of the quart Bunsen when charged 
with sulphuric acid diluted with twelve parts of 



Batteries, Dynamos^ and Accessories, 29 

water in the outer cell, and strong nitric acid in 
the inner cell, may be put down at 1*86 volts, and 
its internal resistance at 0*08 ohm. This will give 
a current of about 23 amperes on a short circuit, 
or 1"78 amperes through an external resistance of 
1 ohm. As gold is deposited from its solutions at 
the rate of 37"31 grains per ampere hour, this 
current will deposit 64' 17 grains per hour. It will 
also deposit 1()550 grains of silver in the same 
time. As, however, silver is best deposited with 
a low E.M.F. of from 1"5 to 1*6 volts, and gold 
with an e.m.f. of r2 volts, the Bunsen has a ten- 
dency to deposit both of these metals in a rough 
condition, unsuited to work that must be bur- 
nished. 

The Bunsen cell is w^ell suited to gilding and 
silvering small articles, such as chains and trin- 
kets slung to fine wires offering a high resistance ; 
but, for plating spoons and forks, and for plating 
on large surfaces, the current from a large 
Daniell, Smee, or Wollaston is preferable, because 
it deposits a coat more adapted to the action of 
the burnisher. The Bunsen cell, however, has 
become a favourite with trinket platers, because 
it is easy to set up and cleanly in working, thus 
causing very little labour in setting up and putting 
away. 

A Bunsen battery may be made as follows : 
Obtain a stoneware jar of quart size or larger, and 
in it place a cylinder of zinc about -| in. thick ; 
inside this zinc cylinder place a porous pot about 
\ in. smaller in diameter but 2 in. higher than 
the stone cell, and inside the porous pot put a 
rectangular stick of carbon, say 2 in. by \\ in. 
by 10 in. to 12 in. long. The zinc cylinder must 
be well amalgamated with mercury, being dipped 
in a dilute solution of oil of vitriol to clean, and 
then placed in a shallow porcelain tray (such as 
photographers use) in which is a quantity of 
hydrochloric acid and mercury. On rubbing the 



30 Electro-plating. 

mercury over it the zinc will be coated inside 
and out. Allow the zincs to stand on end for a 
time to drain the excess mercury off. Fix the 
zincs and carbons w4th brass connections, and 
join the batteries in series — that is, connect the 
zinc of one cell to the carbon of the next, leaving 
a free end of the zinc and of the carbon. The 
batteries must be charged with acid as follows. 
Run the nitric acid inside the porous cell till about 
three-quarters full, and fill the space between the 
porous cell and the stoneware with a mixture of 
1 part of sulphuric acid to 9 parts of water. 

The French Bunsen is made up with sulphuric 
acid in the porous cell with the carbon, tlius pro- 
ducing a constant generator with a lower e.m.f. 
The current from the French Bunsen has an e.m.f. 
of 1"8 volts at starting, but it soon falls to 1'6 
or 1"5 volts when the circuit is closed, because the 
sulphuric acid is inferior to nitric acid as a de- 
polariser. This form is also less troublesome to 
keep in working order than the ordinary Bunsen, 
and it is free from noxious fumes, which render 
the presence of the ordinary Bunsen well-nigh in- 
tolerable in close workshops. 

Nearly all the batteries given in the list on 
p. 25 may be modified. A modification of the 
Bunsen has just been noticed. In the table, 
mention is made of the various strengths of acid 
solutions to be used in the zinc compartments of 
the batteries. These suggest other important 
modifications, the e.m.f. of the battery varying 
with the quantity of acid used. For instance, the 
E.M.F. of the Bunsen charged with a solution of 
one part sulphuric acid and eight parts of water 
may give an e.m.f. of 1-95 volts, but when charged 
with a solution of 1 part sulphuric acid to 10 or 
12 parts of water the e.m.f. may fall to even less 
than 1-80 volts. The Daniell, Smee, and Walker 
may be modified in like manner. 

The Wollaston battery takes the form shown 



Batteries, Dynamos, and Accessories. 31 

by Fig. 10. All the couples of copper and zinc 
plates are contained in separate cells a d of glass 
or porcelain, which hold the sulphuric acid or 
other exciting fluid. The zinc plates are each kept 
adjusted centrally by wooden slips between the 
halves of a doubled copper plate bent round under 
them. The whole set of plates is connected by 
copper strips m, and is secured to the wooden 
frame K ; so it can at pleasure be lifted out of 
the fluid and the action of the battery stopped. 




Fio-. 10.— AVollaston Battery. 



This is one of the earliest galvanic batteries intro- 
duced after Volta's original invention. 

The Wollaston battery is the least costly and 
least troublesome of all the plater's galvanic bat- 
teries, but it is also most inconstant, as its cur- 
rent is apt to fall off rapidly after being set to 
work ; but it recovers its strength after a few 
minutes' rest, and it is a handy battery for such 
short jobs as generally fall to the lot of the 
country jeweller. One form of it may be made at 
home as follows: Get three or four open-mouthed 
jars of glass, stoneware, or porcelain, of any size 



32 ELECTRO'PLATIXG, 

from one quart to one gallon, the larger size being 
preferable ; these are to serve as battery cells. 
Next get some three or four plates of rolled zinc, 
just large enough and long enough to go in the 
jars ; clean the plates well in hot water contain- 
ing washing soda, and rinse them in clean water. 
Pour some water in an earthenware baking-dish, 
about enough to cover a zinc plate ; then pour in 
carefully some sulphuric acid, 1 part for every 
10 parts of water in the dish. In this mixture 
immerse the zinc plates, one at a time, and pour 
on each a small quantity of mercury ; spread this 
over both sides of each plate with a mop made 
of tow containing a few brass wires, and then 
coat them perfectly. This is termed " amalgama- 
ting" the zincs. The acid mixture may be used 
with some more to work the battery, and the 
excess mercury can be used over again. These 
zinc plates have to be suspended to a cross-head 
of wood (each plate between two plates of copper 
in each cell). The wood supports should be cut 
out of hard wood to the shape shown in Fig. 11, 
so as to enclose each zinc plate between two 
pieces of wood, the plates fitting in the recesses 
cut for them. The wood should now be well 
varnished, or, better still, well soaked in melted 
paraffin wax. Each zinc plate can then be 
enclosed between two wooden supports, these 
secured to each other by long brass screws passing 
through both, and the plate held up by a binding 
screw on the top, as shown in Fig. 12. A pair of 
copper plates must now be obtained for each zinc 
plate, the copper being slightly larger than the 
zinc, and of any thickness. They work all the 
better if they are cross-scored with a file, or if 
they have a rough coat of electrotype copper de- 
posited on them ; they work better still if they 
are coated with platinum, but this necessitates 
the use of a battery and a costly platinum solu- 
tion. The copper plates may be secured to the 



Batteries^ Dynamos, and Accessories. 33 

cross-heads on each side of the zincs by very 
short brass screws, care being taken not to let 
any of them touch the zinc plates ; or they may 
be clamped with brass clamps (Fig. 12) sold for 




Fi^ 11.— Part of Battery Plate Support. 




I for Use. 



tlie purpose. When clamps are used, it is always 
quite easy to remove the plates for cleaning, and 
to reverse the zinc plates so as to wear both ends 
equally. The battery jars are charged with an 
acid mixture, made by pouring one part by volume 



34 



r.LECTRO-PLA TIXG. 



of sulphuric acid into twelve parts of water, and 
allowing it to cool before using. The plates are 
suspended by the wooden cross-heads in this mix- 
ture. When it is wished to increase the pushing- 
force (the E.M.F.) of the current, the copper plates 
of one cell are connected by a length of No. IG 
copper wire to the zinc plate of the next cell, 
and so on through tJie whole series of cells, taking 
in as many as may be wanted. When a low- 
tension current of large 
volume is desired, all the 
copper plates of the cells 
are connected together by 
one set of wires, and all 
the zinc plates by another 
set of wires. The cells 
may be placed in a wooden 
tray or in a shallow box, 
and all the cross-heads may 
be secured to a long bar 
of wood, w^iich may be 
suspended to a suppoi't 
above, or to an arrange- 
ment for lifting all the 
plates out of the cells 
when the battery is not 
wanted. This arrangement 
will also be found to be 
most convenient for con- 
trolling the current, as its volume can be 
lessened at any time by exposing a less 
surface of the plates to the action of 
the battery acid. When the battery is not re- 
quired for use, the plates should be lifted out of 
the cells, and if they are not likely to be wanted 
for a few days, they should be well rinsed in an 
abundance of water, to free them from acid. It 
will be necessary to take out the zinc plates occa- 
sionally, clean them, and freshly amalgamate their 
surfaces. This must be done at any time if the 




.^mea 



Batteries, Dynamos, and Accessories. 35 

plates give off a liissing noise, and appear to be 
blackened by the acid. 

The Smee cell is constructed on the principle 
shown in Fig. 13. In a rectangular glass vessel 
are two zinc plates Zn, held together by a screw, 
and between them, well insulated, is a platiuuui 
l^late or a silver plate covered with platinum 
(see Ag.). The vessel is filled with diluted H.2SO4, 
and is made larger than the plates so that the 




Battery of Smee Cells 



zinc sulphate which is forming may not come into 
contact with the plates, and may fall to the 
bottom of the vessel. A battery of Smee cells is 
shown bj^ Fig. 14. In this figure, z and p respec- 
tively indicate the zinc and platinum and their 
connections. It is possible to make up the Smee in 
a similar manner to that described for the Wollas- 
ton, except that platinised silver foil, soldered to 
copper frames, is used instead of copper plates 
for the negative elements, but in all other respects 
the battery may be made like the Wollaston, and 



36 Electro-plating. 

will give similar results, but its action is longer 
sustained after being connected to the work, be- 
cause it does not polarise so soon. The proper 
exciting liquid is a mixture of one part by mea; are 
of sulphuric acid and seven of water, which will 
be found strong enough for all purposes. Fre- 
quently it is advisable to use only one part of 
acid to ten or sixteen parts of water, and to add 
acid as required, taking care, however, that the 
quantity of acid never exceeds one-fourth of the 
original water, for any excess above that quantity 
will be useless, as the liquid will then become 
saturated with the sulphate of zinc. Still further 
modifications may be made in the battery by en- 
larging or diminishing the size of the negative or 
the positive element, or both of these, and in 
altering the size of cell containing them. As a 
rule, the enlargement of elements and cells tends 
to an increased output of current, because the 
internal resistance of the battery is lowered, and 
there is, consequently, more available force for 
the outer circuit. Enlarging the negative element 
will frequently bring about the desired result of 
lowering the internal resistance of the battery 
and increasing its volume of current. This is 
specially noticed in the Daniell, Smee, and Walker 
batteries. 

The Fuller cell (Fig. 15) has an outside stone- 
ware jar with an inner porous pot, the outer jar 
having a plate of carbon in chromic acid or bi- 
chromate of potash solution, with one-quarter of 
its bulk of sulphuric acid. In the illustration a 
part of the porous pot is cut away the better to 
show the zinc. The inner porous pot contains a 
rod of zinc ending in a plug z, the bottom of the 
pot is covered with mercurj^, the remainder of the 
cell being filled with sulphuric acid and water. 
The electromotive force is 1-50 volts. 

One of two charges can be used for a Fuller 
cell. In one the porous pot with the zinc plug is 



Batteries, Dynamos, axd Accessories. 37 



charged with a solution of 1 oz. of common salt 
to 1 pint of water. In the other a solution of 
12 parts of water to 1 part of sulphuric acid is 
used. In using either of these solutions, about 
1 oz. of mercury should be placed at the bottom 
of the porous pot, to ensure constant amalgama- 
tion of the zinc, thereby preventing waste. The 
outer jar, containing the carbon plate, is charged 
with a solution made by dissolving bichromate of 
potash 3 oz. to every pint of warm water, and 
then adding 3 oz. of sulphuric 
acid gradually, stirring with 
a stick. The addition of the 
acid causes the solution to 
become scalding hot, so care 
should be taken to make the 
mixture in a vessel that will 
not crack. All the solutions 
should be quite cold when the 
cell is put up for use. The 
size of the porous pot depends 
on the shape and size of the 
outer one. It should stand 
up about 1 in. above the 
outer pot, and should com- 
fortably hold the zinc plug 
without occupying too much room in the outer jar. 
When a battery is wanted for use for only a 
few minutes at a time, or merely to flash on a 
thin coat of silver to hide defects or discoloured 
patches, the Gassner dry battery may be used. 
This battery needs no attention in the way of 
setting up or cleaning, as it is always ready for 
work, and will furnish current sufficient to gild 
a brooch, scarf pin, or even a bracelet, or to plate 
such an article with a thin coat of silver. The 
large double-carbon square cells should be se- 
lected for this purpose, and the battery should be 
made up of two of these cells in series. They will 
last about two years, without renewal, on such 




15.— Fuller Cell. 



38 El EC TR 0-PL A TING, 

intermittent work as has just been mentioned. 
If used for jobs which will necessitate a constant 
supply of current for more than ten minutes, the 
battery will soon be exhausted. 

The Gassner cell (Fig. 16), one of the earliest 
of dry batteries, is complete in itself, instead of 
being a composite cell made up of inner and outer 
vessels. There is no porous cell of any kind, or 
any outer cell of glass, porcelain, or other break- 
able material. The battery case is of thin sheet 
zinc, Avhich may be made in any form and of any 
size required. The sheet zinc case, which forms 
the positive element, is nearly filled with a paste 
composed of zinc oxide and gypsum, moistened 
with a solution of zinc chloride. A capped cube 
of carbon, bearing a binding screw on its head, 
forms the negative element in the centre of the 
case, where it is surrounded by the conducting 
and exciting paste. The whole is sealed over with 
a composition resembling marine glue. It will 
thus be seen that there is no liquid to spill, nor 
is any required, as the paste is moist enough to 
excite the zinc, and it will retain its moist con- 
dition for any length of time. The cells may 
therefore be laid on their sides, or turned upside 
down, without impairing their working qualities. 
They may be placed in any convenient position, 
regardless of the temperature of the room in 
which they are located. When a Gassner cell is 
exhausted, a strong current of electricity (such 
as that from a battery of Bunsen cells) is sent 
through the cell from carbon to zinc for about 
an hour to regenerate its contents, but the effect is 
<jnly temporary. Other dry cells have equal value. 
The square form of the Gassner cell here re- 
commended is divided by a zinc partition into two 
equal parts, each containing a block of carbon. 
This increases the exposed surfaces of the two 
elements, and ensures a corresponding low in- 
ternal resistance to the cell. There is also a 



Batter I ESy Dynamos, and Accessories. 39 

small cell made, and this is furnished with a 
hollow cube of carbon. The tall oblong form is 
enclosed in a case of vitrified iron, which gives 
additional strength and adds to its appearance. 
Each carbon is furnished with a terminal binding 
screw, as in the Leclanche battery, but a piece of 
stout copper wire is soldered to the zmc case for 




Fiof. l(i. — Gassner Dry Cell. Fio-. 17.— Leclanche Cell. 

connecting purposes. The top of each cell is 
sealed with a resinous composition. 

The Leclanche cell is not suitable for regular 
plating ; but if an occasional plater happens to 
possess one he can use it for small jobs requiring 
current for a few minutes only. The Leclanche 
cell always has a glass outer containing jar which 
is of square shape, for convenience of packing to 
form a battery (see Fig. 17), with a large round 



40 Electro-pla tixg. 

mouth furnished with a lip. The cell complete 
has the top of the mouth, both inside and out, 
for about an inch down, coated with Brunswick 
black, paraffin wax, or similar material, that will 
prevent the salts formed by the contents from 
creeping over the edge. This coating is applied 
by thoroughly cleaning the jar, heating it, and 
either dipping the rim into melted paraffin wax, 
or giving it two or three coats of Brunswick black. 
The porous pot which goes inside the glass jar 
contains a carbon plate with a lead cap, on w^hich 
is a binding-screw with connections. The whole 
of the space between the carbon and the pot, to 
within \ in. of the top, is filled up with a mixture 
of equal parts by bulk of crushed coke or carbon 
and peroxide of manganese, crushed to the size 
of very small peas or rice grains, sifted from the 
dust and packed in as tightly as possible. So as 
to allow the gas formed in working to escape, 
two little pieces of glass tube are embedded in 
the mixture on each side of the carbon, and then 
the top should be sealed up with melted pitch, 
or pitch and resin mixed ; the top of one tube is 
shown in Fig. 17. The whole of the top should 
have two or three coats of Brunswick black, 
working well over the lead cap and into the top 
of the carbon plate, and down the outside of the 
top of the pot for about 1 in. ; dip the bottom 
of the porous pot for about \ in. into melted 
paraffin wax, and the negative element is ready 
for use. The positive element is generally a rod 
of drawn zinc ; if cast it is crystalline and brittle. 
A hole should be drilled in the top, and a stout 
piece of gutta-percha covered copper wire either 
screwed or soldered in. The joint should be well 
covered with gutta-percha or several coats of 
Brunswick black. The zinc should be amalga- 
mated by the following method. With a file re- 
move rough excrescences, etc., and have ready 
two glass jars deep enough to take the zincs ; 



Batteries^ Dynamos, and Accessories. 41 

one of these should be half full of water contain- 
ing about a tea-spoonful of sulphuric acid, the 
other a quarter full of the same mixture with a 
little mercury at the bottom. Dip the rod first in 
the tube with the acid and water to clean it well, 
then into the one with the mercury, and by hold- 
ing it in a slanting position the mercury can be 
easily flowed all over the zinc by twisting it round. 
Wipe off the superfluous mercury with a rag, and 
the rod is ready for use. 

A Leclanche cell is charged by three-parts 
filling the outer jar with a strong solution of 
ordinary sal-ammoniac ; if the jar is more than 
three-parts filled, the salts of the solution will 
creep up. In a few hours the cell will be ready 
for use. Should it not be convenient to wait, 
pour through the little glass tubes in the seal 
some of the solution into the porous pot, and the 
cell will be in working order in a minute or so. 
The chemical action that goes on during the 
working of the cell is this : The zinc, sal-ammoniac, 
and peroxide of manganese are changed into zinc 
chloride, water, and ammonia ; and the oxide of 
manganese is reduced to an oxide less rich in 
oxygen. Using chemical signs, Zn, 2NH4CI, and 
2Mn02, become ZnCl^, H^O -h 2NH3, and Mn-^Og. 
Where a good, full current is wanted for short 
periods at intervals — such as for electric-bell work 
— a cell of this type is suitable ; it is of no use 
where continuous currents are needed — as in 
electro-plating — as it polarises quickly, recover- 
ing itself, however, equally rapidly. It has 
another advantage^action does not go on inside 
the cell unless the circuit is closed and the cell is 
doing work ; therefore it can stand for months 
always ready charged without any fear of the 
zincs being eaten away ; moreover, it is not 
affected by changes of temperature, and it does 
not give off noxious fumes. The e.m.f. of the 
Leclanche cell is 1*60 volts, and the internal re- 



42 Electro-plating. 

sistaiice varies between "75 and "85 ohm in the 
3-pint size ; I'l and 1*2 in the quart size ; and 1'5 
and 1*6 in the pint size. 

With regard to wet batteries in general, cells 
holding from 1 to 10 gallons each, and elements 
of a corresponding size, become a necessity when 
large articles have to be plated, or when a great 
number of articles has to be plated at the same 
time. This necessity may be partly met by em- 
ploying a great number of small cells coupled in 
multiple arc, but small cells thus coupled up soon 
run down, because, being placed on short circuit, 
their charges of acid are soon used up. The best 
work is generally obtained when the elements of 
the battery present a slightly larger surface to 
the liquids within the battery than that of the 
anodes to the solution in the vat. 

Lastly, the current obtainable from a battery 
may be modified by the manner in which the cells 
are coupled together. If the e.m.f is too low, 
the cells may be coupled up in series until the 
required e.m.f. has been obtained ; or, on the 
other hand, if the e.m.f. is too high, it may be 
reduced by taking off some of the cells. It is not 
good practice to couple two or more cells of a 
different style of battery together to obtam the 
needed e.m.f., as the w^eak cells always pull down 
the current to their own level, and the current from 
the stronger cells will heat the solutions in the 
Aveakest, thus impairing the efiiciency of the 
battery. 

Batteries for electro-deposition are fast giving 
place to dynamos, which yield a current in every 
respect more suitable to the w^ork of depositing 
metals th'an that from the best batteries. They 
are also more cleanly in working, less costly, and 
more easily managed. 

Success in electro-plating largely depends upon 
the choice of a suitable dynamo. Dynamos de- 
signed for electro-plating differ considerably from 



Batteries, Dynamos, and Accessories. 43 

those employed in electric lighting work. For 
electro-plating is required a machine capable of 
giving a large volume of current at a low pressure, 
and this must be delivered continuously in one 
direction. Machines for electric lighting work 
are designed to give only a moderate volume of 
current at a high pressure, and this may be of an 
alternating character — that is, a kind of see-saw, 
or to-and-fro movement. 

The difference in the two classes of machines 
may be clearly shown by noting in figm-es the 
relative value of their output. The output of 
dynamos for plating runs from 30 to 3U0 amperes, 
at pressures varying from 5 to 8 volts, whilst the 
continuous current dynamos used in electric light- 
ing are designed for outputs varying from 3 to 
300 amperes, at pressures of from 30 to several 
hundred volts. As 8 volts is the maximum pressure 
needed to deposit metals from their solutions, a 
dynamo giving a current having a pressure of 30 
volts is manifestly unsuitable. 

Another characteristic of the plating dynamo 
is seen in the winding and connection of its coils. 
An electric-lighting machine may have its coils 
connected in series, but an electro-plating machine 
must have the coils so wound as to be shunt con- 
nected, or some special means must be devised to 
prevent the back current from the plating vat 
going through the coils and reversing the mag- 
netism of the machine. Electro-plating machines 
are also run at a slower speed than machines for 
electric lighting. The w^ould-be plater should, 
therefore, avoid all offers of cheap machines that 
have been used in electric lighting. 

It is not necessary to specify any particular 
type of dynamo as being the best, since all makers 
of dynamos are prepared to design and make 
plating dynamos from various types of castings. 
Their value does not depend so much on their 
form as on the perfection of their construction 



44 Electro-plating, 

and fitting from an engineer's point of view, and 
the proper proportion and winding of their coils. 
Firms supplying plating requisites are usually 
prepared to furnish suitable dynamos, and these 
may be generally relied upon as being the best 
for the purpose. 

Some idea as to the general form of a useful 
electro-plating dynamo may be gleaned from Fig. 
18, which shows a dynamo made by Messrs. J. E. 
Hartley and Son. It has a heavy bed-plate of 
iron, on which are two vertical massive iron pro- 
jections wound with covered copper wire. Be- 
tween these projections, near the top, in a channel 
or tunnel hollowed out in the two horns of iron, 
is an axle or cylinder of iron also wound with 
coils of wire, with their ends fastened to a ring 
or wheel of metal divided into segments. This 
cylinder is called the armature, and the ring is 
the commutator, whilst the two vertical projec- 
tions are the field-magnets. When the armature 
is revolved in the tunnel between these field- 
magnets, its coils cut through lines of magnetic 
force, which stream across the tunnel, and this 
action sets up an electric current in the armature 
coils. The current is conveyed from these to the 
segments of the commutator, and is picked up 
from them by metal pads called brushes, which 
rest on the segments. From the brushes, part of 
the current goes around the field-magnet coils to 
strengthen them, and the remainder is available 
for the w^ork of depositing metal. The brushes 
are fixed to a rocker, insulated from the rest of 
the machine, and wire cables lead from this to 
stout binding screws or clamps on a board fixed 
to the top of the field-magnets. Stout wire cables 
convey the electric current from the binding 
screws to other screws fixed on rods placed across 
the tops of the plating vats — that is, the vessels 
holding the plating solutions. From one of these 
rods a number of nickel plates are suspended in 



Batteries^ Dynamos^ and Accessories. 45 

the solution ; from the opposite rod the goods to 
be plated are suspended by metal hooks in the 
solution, and when this is done the electric circuit 
is completed. 

The route taken by the current is from the 
positive or outgoing pole of the dynamo, along 
one of the wire cables to the rod holding the 
anodes, down these into the solution, through the 




. 18. — Electro-plater's Dynamo. 



solution to the articles being plated, then back to 
the dynamo by the other cable attached to the 
jiegative or incoming pole of the machine. This 
route has been explained so that readers may get 
an intelligent insight into the arrangement of 
dynamo and vats, in order that no mistake may be 
made in fixing the machine (see also p. 55). 

A useful dynamo for working small quantities 



46 Electro-plating. 

of plating solutions may be made as follows by 
anyone acquainted with the mechanism of 
dynamo-electric machinery. Procure castings for 
a Kapp or over-type form of field, with cores 8 in. 
in heiglit, 6 in. in length, and 1 in. in thickness, 
and a laininated djuni or shuttle armature 3 in. in 
diameter and 6 in. long. A shuttle armature is 
easier to wind, but more current can be got from 
a drum armature. If a shuttle armature is 
chosen, wdnd it with 1^ lb. of No. 16 cotton-covered 
copper wire, and the fields with 6 lb. of No. 18 
cotton-covered wire, connected in shunt with the 
armature. If a drum armature is chosen, wind it 
with 2 lb. of No. 16 cotton-covered wire, and the 
fields with 6 lb. of No. 18 cotton-covered wire, con- 
nected in shunt. The speed may be low — say, from 
900 to .1,200 revolutions per minute. Copper and 
nickel will require the higher speed. Any steady- 
running motor will drive the machine, which will 
only absorb about 1 man power. 

Canning's shunt-wound semi-enclosed plating 
dynamo with slotted drum armature is shown by 
Fig. 19. Its entire frame, which is also the mag- 
net yoke, is of cast iron of high permeability, and 
is in one piece. The shaft is of mild steel of 
ample strength, and has a keyway for all fixed 
parts. The bearings are bolted to the frame, and 
are lubricated automatically by revolving rings 
running in oil wells. The solid gun-metal bushes 
are easy of access for inspection, and are pro- 
vided with the necessary holes for drawing off 
the oil when it requires renewing. The magnet 
windings have a high electrical efficiency and are 
of cotton-covered copper wire wound on formers, 
built up with ends securely bound with tape, 
thoroughly insulated and coupled to terminals by 
lead eyes soldered to ends of wires. Fringe rings 
are used in all machines above 50 amperes, and 
are easily removed and arranged to keep wind- 
ings in place. The armature core is of the slotted 



Batteries, JDvnamos, axd Accessories. 47 

drum type, composed of sheet-iron plates well 
insulated, clamped between two cast-iron plates 
and securely fixed to the shaft. The armature is 
wound with covered wire, thoroughly insulated 




and firmly embedded in the slots of the discs, 
and held by wire bands which are insulated w4th 
mica from any portion of the armature. The 
armature can be easily taken out by removing the 



48 Electro-pla ting. 

bearing at the pulley end, and is accurately 
balanced. The commutators have a deep wearing 
surface, and are made with copper segments in- 
sulated from each other with mica. The brush 
holders and rockers to carry them are fitted with 
adjustable springs and hold-off catches, and are 
connected directly to a bush or by a flexible 
stranded cable. The rockers are adjustable and 
fitted with clamping screws enabling them to be 
set in any position. The brushes are of copper 
wire encased in gauze. The terminals are placed 
in a convenient position on the dynamo frame, 
and are tinned ready for the copper conductor to 
be soldered in. The driving pulley is of cast iron, 
rounded on the face, and is securely keyed to the 
shaft. The dynamo will stand an overload of 25 
per cent, for one hour without undue heating or 
sparking, and a greater overload for short periods. 

Having received a dynamo from the maker, its 
position in the workshop should be determined. 
It is not necessary to have it close to the plating 
vat, as the plater can easily look after the machine 
if it is at one end of the shop and the plating vat 
at the other. It should not be fixed in another 
apartment out of sight, or in any position where 
it is likely to pick up metal dust and other dirt. 
When it is revolving, a current of air sets in 
towards the armature, and draws wath it any 
dust that may be flying about the shop. As it is 
a strong magnet, it will attract to itself any small 
particles of iron, steel, nickel, or cobalt, such as 
filings of those metals. It is therefore advisable 
to bolt it down firmly on a strong bench raised 
above the floor. As the machine is driven at a 
high rate of speed, and this sets up a strong 
vibration of its parts, the bench must be strong 
and firm to lessen as much as possible the 
vibration. 

The dynamo should be driven from a counter- 
shaft furnished with fast and loose pulleys driven at 



Batteries, Dynamos, and Accessories. 49 

a lively speed, to obviate the necessity of driving 
with a tight belt on a large driving wheel. It is also 
best not to have the driving wheel of the counter- 
shaft directly over the dynamo. The machine works 
best when driven with a wide, long belt, as this 
ensures a better grip of the pulley on the arma- 
ture spindle. Most makers advise the speed at 
which the machine should be driven, and this may 
be ascertained by means of a little speed indicator. 
The direction in which the dynamo armature 
should revolve is indicated by the position of the 
brushes ; ifc must never be run against them 

Having fixed the machine and started the 
machinery to work it, an attempt must be made 
to start the djmamo so as to get the best results 
frcm it. See that when turned by hand all its 
parts move freely without a hitch ; see also that 
the oil cups are provided with oil. Now start the 
machine and connect it by means of two thick 
wires to an ammeter — that is, an instrument for 
measuring the volume of the current. This is a 
most important instrument, and, if not provided 
in the outfit in connection with a resistance board, 
it should be purchased afterwards, as it is to the 
plater what the foot-rule is to the mechanic. 
When connected to the ammeter, note the deflec- 
tion of the needle or hand of this instrument, then 
alter the position of the brushes until the best 
effect has been obtained — that is, the largest num- 
ber of amperes indicated on the dial. This altera- 
tion may be effected by loosening the screw which 
holds the rocker to its insulating collar, and 
moving it, together with the brushes, until the 
best angle has been obtained, then fixing the screw 
tightly. 

The best materials for brushes are pads of 
copper gauze, backed with strips of spring brass, 
which gently press the pads, and keep them in 
contact with the commutator. The volume of 
current obtainable from a machine is influenced 



5° 



Electro-pla ting. 



by the lead and angle of contact of its brushes on 
the commutator. From time to time these pads 
and the commutator must be examined and re- 
paired, and the worn pads being made good, the 
slits between the bars of the commutator wiped 
with a piece of card to clear out particles of 
copper, then oiled, and the oil wiped off again 
with a piece of rag. Beyond keeping all connec- 
tions cleaned, and the working parts, bearings, 
etc., well oiled, it will be found that the machine 
does not require any more attention than that 
already indicated. 

After the dynamo has been fixed and tested, 
connect the leading cables to its terminals, and 
lead them to the positions likely to be occupied 
by the plating vats. If several of these are likely 
to be laid down, or even if only two of such vats 
are to be used, it will be advisable to lead the 
cables from the machine to a couple of stout 
copper rods supported in wooden cleats on the 
walls of the plating shop, these rods being fur- 
nished with suitable clamps, and short cables led 
from these main arteries to the vats, as shown in 
the illustration. 

The plating dynamo should be kept thoroughly 
clean. The holders should be fitted with springs 
to ensure a light even pressure of the brushes 
on the commutator. If these press too hard, 
they will soon wear deep grooves in the commu- 
tator bars, and if the springs are too light, the 
brushes are liable to break contact occasionally, 
when the sparks will burn both brushes and com- 
mutator. Keep the tips of the brushes neatly 
trimmed square, and free all parts from copper 
dust before starting the machine. If the bars 
show signs of grooving, -throw off the brushes 
and work out the grooves with a flat stick covered 
with emery cloth, whilst the machine is running 
idle, then wipe the commutator with a rag smeared 
with vaseline. Always keep the machine well oiled. 



Batteries^ Dynamos, and Accessories. 51 

Connecting the dynamo with the vat are copper 
cables, and for these the following sizes may be 
used. For 10 amperes, seven strands of No. 18 
s.w.G. : 20 amperes, seven strands of No. 16 s.w.G. ; 
30 amperes, nineteen strands of No. 18 s.w.G. ; 
50 amperes, nineteen strands of No. 17 s.w.G. ; 75 
amperes, nineteen strands of No. 15 s.w.G. ; 100 
amperes, nineteen strands of No. 14 s.w.G. ; 150 
amperes, thirty-seven strands of No. 15 s.w.G. ; 
and for 210 amperes, thirty-seven strands of No. 14 
s.w.G. from dynamo to vat. One of the cables 
should be in one length. The other cable should 
be in two or three lengths, the first from 



lW..iCA N N I N G ,S C° : ^B\ R M 1 7 J S H A M 





Fig. 20.— Conducting and Supporting Rod. ^^ 

the dynamo to a resistance board near the vat ; 
then a short length from the board to the amme- 
ter ; and then a short length from the ammeter 
to the vat. It matters very little which line is 
thus broken, but it is customary to have the line 
leading from the positive terminal of the dynamo 
to the anode system on the vat thus divided. 
The insulating covering must be stripped from the 
ends of the cables, the w^ires soldered together, 
then soldered into suitable connecting sockets. 

As it is possible entirely to neutralise the con- 
ducting capacity of a cable by a bad joint or a 
bad connection, see to it that all joints are well 
made and soldered, and all parts connected by 
clamps and under screws made quite clean with 
broad surfaces of clean metal in contact with clean 
metal at all points. 

Each vat must be furnished with two rods of 
stout copper or brass (see Fig. 20) running the 
whole length of the vat, and furnished with brass 
connecting clamps, to connect with the cable lead- 



5 2 El EC TR 0-PLA TING. 

ing from the dynamo. These rods should be | in. 
in diameter for small vats, increasing to 1 in. or 
1^ in. for larger vats. It is advisable to have 
three such rods when a large quantity of work is 
in the vat, the articles to be plated being sus- 
pended from the centre rod, and the anodes from 
the two side rods. In this case the two side rods 
must be connected together by a stout piece of 
cable across the vat, at the end furthest from 
the dynamo. The rods must be connected to the 
main leads from the dynamo by stout cables, 
capable of carrying the full load of current 
required. 

The slinging wires mentioned on p. 19 depend 
from the rods, and have at their lower ends the 
hooks which carry the anodes and articles to be 
plated. 

The resistance board (Figs. 21 and 22) is a slab 
of hard wood or slate, furnished with six or more 
brass studs on the upper edge, and eight or more 
brass contact pieces screwed on in the position 
shown. Lengths of stout copper wire, graduating 
in size, are fixed to some of the brass pieces and 
pass around the studs ; then, German silver wires, 
offering ten or eleven times the resistance of the 
copper wires, are fixed to the remaining pieces 
and pass around the other studs, thus forming a 
zigzag line of wire of graduated resistance from 
one side of the board to the other, as illustrated. 
A brass lever is pivoted so as to sweep the semi- 
circle of brass pieces and make the connection 
with each in turn. This central stud may be 
connected to a large binding screw at the bottom 
of the board, and one end of the cable is fixed to 
this screw. At the opposite end of the semicircle, 
one of the brass pieces is similarly connected to 
another section of the cable. 

The resistance board enables the plater to 
control the current from the machine ; when the 
switch lever rests on the contact piece connected 



Batteries, Dynamos, and Accessories. 53 

direct to the cable, the circuit has no additional 
resistance, but when one of the lengths of copper 
wire is thrown into the circuit by moving the 
switch lever, resistance is added, and, when the 




Fiar. 21. — Resistance. 



1 ■ 
1.: 


> 


• ' 


t 


• ' ' 


'■'1 


\ 

li 


ii: 


1 
1 






M 




illi: 


i\t 


It 


:;!i 


,:jj 1 




Fig. 22. — Resistance Board, 
combined with Ammetei'. 



lever rests on the last brass piece, all the resist- 
ances are thrown in. Thus the plater is enabled 
to silver a small article safely, even w^ith current 
from a very large dynamo. The switch is equiva- 
lent to a tap in a water-pipe, each wire taken in 



54 



Electro-pla ting. 



by it acting like the plug of a tap in narrowing 
the hole through which the water flow^s. A resist- 
ance board must be placed to each vat to control 
the flow of current through it as required by the 
plater, and when an ammeter is combined with 
the board (as shown in Fig. 22), the current passing 
at any time can be seen at a glance. 

The ammeter (Fig. 23) measures the current, 
and is often fixed to the resistance board for ready 
reference (see Fig. 22). As the rate at which the 
silver is deposited depends on the current through 
the vat, and as the character of the deposit is 
greatly influenced by the rate of deposit, this 
instrument is of great importance, for by it the 
plater can determine how mAicli silver is being 
deposited. The dial of an ordinary ammeter 
show^s the current in amperes, 1 ampere being 
that current which will deposit 52 gr. of silver in 
one hour on 1 sq. ft. of suitable surface, in a fit 
condition for polishing. Thus, in the special in- 
strument made by T. Morris and Co., Birming- 
ham, and illustrated by Fig. 23, the lower scale 
shows also the w^eight of silver deposited per hour. 

The voltmeter is similar in external appear- 
ance to the ammeter, but the readings on its dial 
are in volts. From its readings the plater can 
adjust the brushes of a dynamo and regulate its 
speed so as to get the right voltage. Experience 
has proved that the silver in a silver-plating solu- 
tion may be separated from its salt and deposited 
in a good condition at as low a pressure as 2 volts ; 
but this may be increased to 3 or even 4 volts 
without altering the condition of the deposit very 
m.uch. However, when the pressure exceeds 4 
volts, there is a tendency to a loose .and powdery 
deposit, which gets more pronounced as the pres- 
sure is increased. A voltmeter is therefore useful, 
but, its coils being w^ound Avith fine w^ire of high 
resistance, it must be placed in a shunt bridging 
the two main lines, and furnished with a switch 



Batteries^ Dynamos^ and Accessories. 55 

to cut the voltmeter out of circuit after the 
dynamo has been adjusted to the required pressure 
(see Fig. 24). 




Fig. 24.— Diagram of Electrical ^i^^^e 
Connections. 




Fig'. 23. — Ammeter showing Rate of Deposit. 

The diagram of electrical connections presented 
by Fig. 24 should be carefully studied. 



56 



CHAPTER III. 

APPLIANCES FOR PREPARING AND FINISHING WORK. 

Chief among the appliances used in preparing 
rnetal for plating is the polishing lathe. In order 
to "produce a polish on the work, the first process 
is by file, scraper, or some similar tool, to remove 
the rough surface the metal has received in forg- 
ing or casting ; and, to do the work quickly, the 
instrument taking the place of the scraper or file 
must move at considerable speed, and the article 
must be held against it. The same method is 
required with the further processes of polishing. 
Figs. 25 to 27 show three kinds of machines suit- 
able for this work. 

Fig. 27 illustrates the machine more generally 
used where steam power can be applied. The 
cast-iron standard is firmly bolted to a block of 
wood or stone, and has adjustable bearings at the 
top for a circular spindle to revolve in ; each 
bearing has a lubricator in the centre to supply 
the spindle with oil. The spindle has fast and 
loose pulleys in the centre, and at the ends devices 
to hold the emery-wheel, grindstone, buff, or 
dolly, as may be required. The ends of the 
spindle should be threaded with a coarse taper 
screw which enters a hole in the boss of the 
brush or bob, and holds it firm whilst revolving. 
Large lathes are furnished with flanged plates at 
one end (see Fig. 27) in addition to the taper 
screws. These plates support calico mops, and 
grip the sides of emery wheels. 

Polishing lathes must be firmly bolted down on 
benches not liable to great vibration, and run at 
a speed of 1,400 revolutions a minute in polishing 



Appliances for Preparing Work. 57 

silver. For polishing steel or other hard metals 
they may be run at a higher speed, up to 2,500 
revolutions per minute. The brushes used witli 




Fig. 25.— Treadle 
Polishing Machine. 



Fig. 2G.— Bench 
Polishing Machine. 



these lathes differ in size and material according 
to the work required from them. 

A simple machine that may be fixed to an 
ordinary bench and worked by foot is illustrated 



58 



Electro-pla ting. 



by Fig. 26. A treadle device is fixed to the floor 
and carried by a standard having a plate to secure 
it to the bench and an upper pillar to take the 
wheel, buff, or dolly. This is the most simple 
construction that can be adopted for the work. 
The wearing portions are few in number, and can 




^(tt|Huituu?m.JJu(»umvtim:>jM<i ^»^'^ 




Fio-, 27. — Power-driven Polishing Machine. 
Figs. 28 and 29.— Spindles for Mops and Dollies, 

easily be replaced, but considerable speed, say 
3,600 revolutions per minute, is easily obtained. 
Fig. 25 illustrates a grinding or polishing machine, 
having the same treadle movement fixed between 
standards, and with a small bench at the top, on 
which two bearings for the spindle are fixed. 
Alternative forms of spindle are illustrated by 



Appliances for Preparing Work. 



59 



Figs. 28 and 29, which show the various ways in 
which the wheels, buffs, etc., may be fixed to suit 
the work required to be done. 




Fig. 30.— Combined Treadle Scratch Brush and Polishing' 
Lathe. 

A combined grinding, polishing and scratch- 
brushing machine is illustrated by Fig. 30. 
The height of the centre of the spindle is 
3 ft. 10 in., and there is provision for two speeds. 



6o Electro-plating. 

A powerful emery wheel machine, arranged for 
power driving, is a most useful tool ; it is, 
indeed, indispensable where much work has first 
to be surfaced before it can be polished and plated. 

The materials used in polishing metals with 
the lathe are : Emery wheels for grinding down 
rough forgings and castings ; grain emery for use 
with bobs in taking out rough file marks and 
scratches in iron and steel ; fine emery for getting 
a better finish ; glass-cutter's sand for grinding 
brass and gun-metal castings ; Trent sand for 
taking out rough file marks and scratches in brass ; 
Sheffield lime for imparting a finish to brass work, 
etc. ; Tripoli composition of three grades for finish- 
ing nickel-plated work, and also silver-plated 
fittings ; rouge in several grades and qualities for 
finishing silver-plated fittings and nickel-plated 
brass work. 

Rottenstone and flour emery together make a 
good material for polishing iron and steel. The 
materials should be formed into a cake or slab by 
mixing with boiling suet and then running into 
square or oblong moulds, and using cold with the 
buffs. Crocus and rottenstone mixed in the same 
way with a little rouge form the best combination 
for brass or copper and kindred materials. Calico 
dollies and mops are used with the powders dry 
to give the finishing effects. 

In the preparation of articles to be plated, 
bobs (or buffs) and mops are employed. Bobs 
are of two kinds : one, formed of a disc of hard- 
wood, having its edge coated with bull-neck 
leather (see Fig. 31), while the other is formed of 
a solid disc of felt. Other varieties have felt or 
buff leather on their rims, whilst some are made 
of solid bull-neck, or of walrus leather. The sizes 
vary from 3 in. to 18 in. in diameter, and from 
I in. to 2 in. in thickness. 

To make a wooden bob, first select a piece of 
hard, well-seasoned M^ood and turn a true disc in 



Appliances for Preparing Work 



6i 



a lathe. Then get a strip of the required covering 
material as wide as the wood disc, and long 
enough to go round and meet with butt edges. 
Next prepare some good glue and roll the edge 
of the disc in it whilst hot; then put on the 
leather or the felt, and secure this to the wood 
with long steel tacks, so driven in as to be easily 
pulled out when the glue is firm. At the end of 
twelve hours these tacks may be withdrawn, and 
wooden pegs dipped in glue driven in the holes ; 




Fi-. :{]. Fig. X\. 

Figs. ;u to 33. — Leather-covered Bobs. 



then true the whole in a lathe. The bob is then 
ready for the grinding material, which may be 
emery, sand, or tripoli, the material and grade 
being selected to suit the work in hand — emery 
for iron and steel, and tripoli for copper and 
brass. The abrasive is spread on paper or in 
a special trough in an even layer, and the rim 
of the bob is first rolled in the hot glue, then on 
the layer of powder until a sufficient thickness 
has been taken up, then it is set aside for another 
twelve hours to get firm. Solid leather or solid 
felt bobs are similarly coated. These bobs are 
employed to grind down rough surfaces and render 
them comparatively smooth. 

Fig. 32 illustrates a better plan of making an 



62 Electro-plating, 

emery bob. Four pieces of wood are glued to- 
gether with their grains crossing, and then cut 
out or turned to circular form. Round the edge 
is securely fixed a thick piece of buff leather, 
fixed and coated with emery as before. The 
centre hole carries a brass boss that is screwed 
to fit the end of the spindle, or has a plain hole 
to fit on the spindle between the collars, as shown 
in Fig. 27, p. 58. 

Fig. 33 shows the construction of a leather- 
covered bob or buff of large size. The wood is of 
wedge-shaped sections, securely fitted and fixed 
together and held by brass or iron rings ; the 
outer edge is covered with leather as before 
described. 

A solid leather bob with a rim of thick leather, 
either bull-neck or sea-horse, may be turned in the 
lathe to suit various shapes of mouldings and 
ornaments (see Fig. 34). The central holes in 
these bobs screw on the point of the spindles 
shown in Fig. 27. The article to be polished is 
held against them, and the emery powder held 
at the point of contact. 

A pressed felt bob can be used in place of a 
leather bob in many cases, and more often for the 
further polishing with crocus or rottenstone. It is 
fixed to the spindle in the same way as the leather 
bobs already illustrated. 

Another method of making a bob may be here 
described. It is of w^ood covered with felt. Two 
discs of well-seasoned beech, of the required dia- 
meter and half the thickness of the desired disc, 
are glued together side by side, with their grains 
opposite, and then left under pressure until quite 
firm. The disc is then turned true, and a number 
of small grooves are cut in its circumference. A 
strip of thick felt of the required width and length 
is laid out on a bench, the rim of the w^ood disc is 
run in some good hot glue until well coated and 
warm, and is then run along the felt under pres- 



Appliances for Preparixg Work. ' 63 

sure, the felt being made to cling close to the 
wood, and afterwards secured to it with long 
tacks. When the glue has become firm and hard, 
the tacks are withdrawn, and wooden pegs, dipped 
in glue, driven into the holes, as already de- 
scribed ; then the whole is trimmed true with a 
sharp knife. The felt-covered disc is rolled in 
hot glue, and then coated with emery in the usua^ 
way. 

The emery employed in polishing bobs varies 
with the work to be done. A bob for the first 
roughing down is usually coated with No. 60 
emery. Then follow bobs coated with Nos. 80, 
120, and 140, the last being used to get a finishing 
polish on steel before employing a mop or dolly. 
Emery-coated bobs cut iron and steel with great 
rapidity. The friction generates heat, and the 
article becomes polished, this action being inten- 
sified by the pressure. 

To polish quickly a number of articles with the 
aid of emery-coated bobs or buffs, arrange them 
on a bench at hand, whilst a box, tray, or bench 
is placed on the other side. As each article gets 
too hot to be held it is thrown into the box, and 
another article is reached from the bench, so 
treating all in succession, and going over them 
again after they have got cool in the box. 

For cycle frames and handle-bars, an emery 
tape machine (Fig. 35) is preferable to a polishing 
lathe and bob. The emery-coated tape or band 
is run over pulleys, and the bars are held to it 
whilst running ; by this means every part of the 
bar can be reached easily and can be speedily 
polished. In Fig. 54, a shows the spindle for 
carrying bob, mop or wheel, b the fast and loose 
pulleys, and c the emery tape. 

When a polishing lathe is not available, and 
a few small and plain articles have to be surfaced, 
a buff stick (Fig. 36) may be used. This is a 
wooden stick with buff leather firmly glued to it, 



64 ' Electro-plating. 

the most suitable leather being the tough, rough- 
grained leather used in soldiers' belts. Buff sticks 
are made in various widths to suit the work in 
hand, the broad buffs being used for polishing 
broad plane surfaces ; and the narrow, thin buff 
sticks for giving a polish to grooves and hollows. 
They are used with finely-powdered rottenstone 
and oil, or with finely-powdered crocus, to give a 
finishing polish by hand to articles about to be 
plated. 

For removing the scratches left by emery bobs, 
emery wheels, or tape machines, revolving mops, 
known also as dollies, are used. These are of 
leather or calico (see Fig. 37), and render the 
surface of the metal quite smooth. They are 
made chiefly from thin tough leather, such as 
basil leather, and chamois leather, and from 
various grades of calico, the finest being the soft 
variety known as swansdown calico. Basil leather 
mops may be from 3 in. to 12 in. in diameter and 
from \ in. to 4 in. in thickness. They are made of 
several discs of basil leather, cut and laid true 
on each other, between two smaller discs of thick 
leather, to form the bosses, which are then secured 
by long iron rivets passing through the whole mass 
of leather. These mops are very useful with 
tripoli compo in preparing surfaces of copper, 
brass, and other soft metals. 

Chamois leather mops are made in a similar 
manner, but are chiefly used to produce a high 
finish on jewellery. Sometimes these leather mops 
are stitched spirally to keep them more compact 
whilst revolving. 

Calico mops are made similarly. The thickest 
and coarsest calico is employed for mops used in 
preparing the w^ork with tripoli compo, etc., and 
the finer grades for finishing the plated articles 
with rouge compo. The bleached varieties of 
calico are, as a rule, harsher in texture than the 
unbleached, and are used in making the mops for 



Appliances Pok PinisNIng Work. 



65 



cutting out scratches, and are then followed by 
mops made of unbleached calico charged with 




Fig. 34.— Sections of Bobs. Fig. 35.— Emery Tape Machine. 
Fig. 36.— Buff Stick. Fig. 37.— Calico Mop. 

rouge compo to give a higher finish. Calico mops 
run from 6 in. to 18 in. in diameter, and have 



66 



Electro-pla ting. 



from 50 to 105 folds to the inch of thickness 
according to the quality and thickness of calico 
employed. Swansdown calico mops run from 6 in. 
to 12 in. in diameter, and have from 24 to 60 folds 
in thickness, or about 24 folds to the inch. 

The polishing mops and materials used in 
finishing plated ware should be kept in boxes, to 
prevent gritty dust getting into them. Each kind 
of mop and polishing compo. should have a 
separate box, and special attention should be paid 
to guard finishing mops and compos, from con- 
tamination with those of a lower and coarser 
grade. The same remarks 
apply to all chamois leather, 
rags, soap, and burnishers 
employed in finishing silver- 
plated articles. 

The final polish to brass 
and similar soft metals is 
given with tripoli in its 
various grades, and with 
rouge on calico mops, these 
also varying in coarseness 
or fineness with the re- 
quired finish of the work. 
Ai'ticles to be nickel-plated should be finished off 
smooth, so as to leave little polishing afterwards, 
because deposited nickel is very hard and not 
easily rubbed down with mops. The final polish- 
ing is done with fine grade tripoli and with 
Sheffield lime. 

Where the article to be polished is very orna- 
mental and the work very fine, a circular brush 
may be employed. This brush may be of fibre 
or mixed fibre and bristle. A woollen brush is 
shown by Fig. 38. Canning's circular brushes are 
of special construction, as is evidenced by the 
sectional view given by Fig. 39. 

Scouring brushes employed at the scouring 
tray are made of coarse bristle or fibre, w^th 




38.— "Woollen 
Brush. 



Appliances for Finishing Work. 



67 



wooden backs and long handles, similar in shape 
to plate brushes or spoke brushes, or as shown 
by Fig. 40. They are made in various sizes, from 
11 in. to 13 in. in length, and with from one to six 
rows of bristles, which also vary from soft to stiff 
and "extra stiff," to suit the requirements of the 




Fig. 30. 



Fio-. 40. 



!iir' 



Fig. 41. 



Fig. 39.— Section of Circular Brush. Figs. 40 and 41.— 
ScourinsT Brushes. 



work. A scouring brush without a handle is shown 
by Fig. 41. 

The only brushes admissible in the potash tank 
are those made of cotton, two forms of which are 
shov/n at Figs. 42 and 43. They vary in length 
from 13 in. to 16 in. 

Scratch-brushes are brushes furnished with 
bunches of brass wire instead of hair or bristles. 



68 



Electro-pla ting. 



They are made in a great variety of shapes and 
sizes, and the wire also varies greatly in softness. 
The simplest form is a wisp or bunch of the 
scratch-brush w^ire bound round with soft copper 
wire, as shown at Fig. 44. The next is the straight 
or bent hand scratch-brush shown by Figs. 45 and 



Fig. 42 



Fig. 4:5. 



Fig. 44. 




Fig. 4(;. 



Figs. 42 and 43.— Potash Brushes. Fig. 44.— Scratch-knot. 
Figs. 45 and 4f5.— Hand Scratch-brushes. 



46. Then there are circular brushes in great 
variety ; and attention is directed to Figs. 47 to 
56 (see p. 69), the inscription given to each figure 
being sufficient to explain the purpose of the 
particular shape. 

Large and heavy brushes with coarse wire 
are used to cleanse the articles from dirt before 



Appliances for Finishing Work. 69 

plating. The smaller ones are for brushing silver 
deposits when first taken from the vat, and are 




Fi^. 47 — Biaba AViit Biiish Fig' 48.— Crimped Wire Cup 
Brush. Fig-. i9.— Turk's Head Cup Brush. Fig-. 50.— 
End Brush. Figs. 61 and 52. — Watch-case Brush. 
Fig. 53. — Inside Thimble Brush. Fig-. 54. — Inside Box 
Brush. Fig-. o5. — Inside Ring- Brush. Fig. 56. — 
Bottom Brush. 



7 o Electro-pla ting. 

made in various shapes to fit peculiarities in out- 
side surfaces, as well as the inside parts of tea- 
pots, mugs, thimbles, rings, tubes, etc. Some are 
furnished with bunches of very fine and soft brass 
wire, some with bunches of German silver w^ire, 
and some have the fine wire crimped to make it 
more elastic. The softer and finer kinds are used 
for gold work and for delicate articles. 

These brushes are run on the spindle of an 
ordinary light polishing lathe furnished with a 
hood or open box over the brush to protect the 
workman from splashes of the lubricant ; this is 
generally stale beer, or beer diluted with Mater. 
Soapy water may be employed as a substitute, but 




Fig-. .57. — Scratch Knot Lathe. 

soon becomes offensive after being used ; and weak 
linseed tea and a decoction of marshmallows 
have been employed. The lubricant may be held 
in a small cistern over the hood, with a tap and 
pipe running down immediately over the scratch- 
brush. • A tray beneath the brush catches the sur- 
plus drops, which are conveyed by a pipe to a 
vessel beneath the bench on which the lathe is 
fixed. The lubricant prevents the fine brass dust 
worn off the scratch-brush being embedded in the 
silver and thus giving it a yellow or stained tint, 
only a few drops applied occasionally being 
sufficient. 

A scratch knot lathe (Fig. 57) is a polishing 
lathe upon whose spindle has been mounted a 
chuck holding eight or twelve wire scratch knots, 
and it forms a most efficient appliance for prepar- 
ing work. 



71 



CHAPTER IV. 

Silver-plating. 

The art of silver-plating is an ancient one. Metal 
workers in olden times learned how to overlay in- 
ferior metals with plates of silver, and, later, dis- 
covered how to make the silver coat adhere by 
soldering to the metal beneath, being then able 
to use thinner plates of silver, which were, how- 
ever, thick when compared with the thickest 
electro-silver-plating now done. 

To electro-plate with silver, the article must 
be immersed in a solution of silver, and electricity 
be passed through this, certain other conditions 
being also complied with. 

More care must be taken in the cleansing of 
articles to be silver-plated than in those to be 
electro-gilded. Gold-plating solution is used hot, 
and will dissolve remaining traces of animal 
matter, but the silver solution is used cold, and 
has no such cleansing or detergent effect on dirt 
left on the surfaces of goods intended to be sil- 
ver-plated. It is necessary, therefore, to free the 
surface from the least trace of dirt of any kind, 
whether in the form of rust, verdigris, tarnish, 
or any other kind of corrosion, or in the form of 
oil, grease, lacquer, sweat, or other animal matter. 
The touch of a soiled finger on the prepared sur- 
face is sufficient to cause the silver to strip off 
from that spot when the scratch-brush or the 
burnisher is applied. 

All deep scratches, dents, cracks, and pits 
must be removed before goods are plated ; all 
necessary repairs must be done, avoiding an ex- 
cess of soft solder ; and in the case of re-plating. 



7 2 Electro-pla ting. 

all the previous coats of silver or of nickel must 
be removed, and the surface polished. Instruc- 
tions for stripping electro-deposited metallic coats 
are given on pp. 145 and 146. 

Rust, verdigris, and other metal oxides can 
generally be loosened, and sometimes removed 
entirely, by immersing the corroded article in a 
pickle made of a diluted mineral acid, or a mix- 
ture of those acids, and then swilling in clean 
water. Green verdigris and similar forms of cor- 
rosion may be removed by dipping in a mixture 
of equal parts sulphuric acid and water, to which 
has been added a half part of nitric acid and a few 
drops of hydrochloric acid. The articles should be 
strung on a wire, and swilled in the dipping mix- 
ture for a few minutes, until the corrosion has 
been loosened, and then rinsed in plenty of clean 
water. After this, they may be brushed w4th an 
old scratch-brush, and again swilled in water. If 
the verdigris is not all off, they must be again 
swilled in the acid pickle until quite clean. 

A mixture of 1 part of sulphuric acid in 20 
parts of water will loosen the oxides of copper 
and zinc on these metals and their alloys. The 
alloys of these metals may have many names, but 
are to be regarded by the plater as brass, and 
treated accordingly. If the surface of a copper 
or brass article is deeply corroded and green, it 
may be necessary to use a stronger pickle, com- 
posed of 3 parts of sulphuric acid. If parts of 
nitric acid, and 4 parts of water. Rust on iron 
and steel may be loosened by immersion in a 
pickle composed of sulphuric acid 6 parts, muriatic 
acid 1 part, water 160 parts. The oxides of lead 
and tin may be loosened from these metals and 
their alloys (pewter, Britannia metal, soft solder, 
etc.) by immersion in a hot solution of caustic 
alkali, such as caustic potash or caustic soda. 

Lacquered goods must \yd steeped for an hour 
or so in warm methylated spirit, and then trans- 



Silver-plating. 73 

ferred to a strong solution of ammonia, to loosen 
the lacquer. They should then be well brushed 
with an old scratch-brush or bristle-brush, and 
rinsed in hot water. Use old brushes for this 
purpose, as it will not be advisable to use the 
same brushes for brushing the surfaces of finished 
goods. 

Mere tarnish may be removed by soaking for a 
short time in a strong solution of cyanide of 
potassium, to which has been added a few drops 
of liquid ammonia. 

Metals are often not only corroded, but also 
dirty with grease, oil, or other animal matter 
capable of resisting the action of acid pickles ; 
and in such cases it is advisable to swill them first 
in the hot alkali solution, then in hot water, and 
rinse in cold water before immersion in the acid 
pickle. The caustic alkali solution is made by dis- 
solving \ lb. of caustic soda, or caustic potash, or 
crude American potash, in each gallon of water 
contained in a wrought-iron tank. 

The acid pickles should be mixed and con- 
tained in vessels made of vitrified stoneware. It 
should be understood that vitrified stoneware is 
the only suitable material for receptacles for acid 
pickles, and plain wrought-iron for those for 
caustic alkalies. The mixed acids will undermine 
and dissolve the glaze from ordinary earthenware, 
and also the enamel from iron. Caustic alkalies 
also dissolve enamel, and extract the zinc from 
galvanised iron, and the tin from tinned vessels. 

For dipping small articles, baskets of the 
shapes shown by Figs. 58 to 60 are often very use- 
ful. When the basket is in the pickle it should 
be shaken about well to allow the liquid to get 
at the entire surface of the work. 

After all corrosion and dirt has been loosened, 
the surfaces of the articles to be silver-plated 
should be well brushed with a hard brush in water 
to remove loosened dirt from crevices and pits. 



74 Electro-pla ting. 

This may be done with an old scratch-brush made 
of wire, if preferred. An examination of the sur- 
face will then reveal numerous scratches, dents, 
and pits, some being due to corrosive action, and 
many to hard usage. These must all be removed, 
for the surface must be made like a new surface, 
all defects being made good before the silver is 
deposited upon it. Dents and misshapen parts 
can be put right only with the aid of hammers, 
pliers, etc. At one time all scratches and pits 
were also laboriously removed by hand, being first 
filed and scraped, rubbed with sand or emery, 
then with water-of-Ayr stone, and polished with 
fine abrading powders. Now the work is nearly 
all done on polishing lathes with revolving 
brushes, dollies, etc., resulting in a great saving 
of time, and in a higher finish (see Chapter III.). 

Scratches on the backs of watch-cases and 
lockets, and pits left from corrosion in other 
articles, must be taken out with a fine file, and 
the file marks rubbed out by grinding with water- 
of-Ayr stone, after which the surface should be 
scoured with a cork dipped in powdered pumice, 
then polished bright in the usual way. Spoons 
and forks should receive similar treatment. Al- 
though the cleansing of goods to be silver-plated 
is so important, there is no need for such a very 
finely polished surface for silver-plating as for 
electro-gilding, since the coat of silver can be got 
up afterwards ; but the same care will be needed 
to get a uniform surface, free from scratches and 
pits. 

After the polishing, the articles will be found 
to be thinly coated with grease or oil, which is 
removed by swilling in the hot caustic alkali 
pickle, and rinsing in water. This process will 
probably coat copper, brass, and similar soft alloys 
with a film of black oxide which must be removed 
by scouring. For this purpose, the article is held 
on the tray with the plater's left hand, the scour- 



SlLVER-PLA TING. 



75 



ing brush is clipped in water, the surplus shaken 
out, the brush dipped in the pumice powder, and 
the article is then brushed to and fro until every 
trace of oxide is removed. When it is rinsed in 
water, it should be quite clean, with a uniformly 
dull surface all over it, which renders the surface 
suitable to take and hold the silver coat. 

The article must now be weired — that is, at- 
tached to the wire which will hold it in the plating 
solution — then rinsed in the mercury pickle to 




Fig. 60. 



Figs. 58 to ()0. — Dipping Baskets. 



impart a thin coat of mercury, again rinsed in 
water and transferred to the plating bath (for the 
composition of which, see pp. 79 to 81), where 
deposition should begin at once. However, in 
many cases, a preliminary coating with copper is 
necessary. 

Iron, steel, and zinc goods, and, preferably, 
also those of lead and its alloys, such as pewter 
and Britannia metal, must be coated with copper 
after they have been scoured, before they can be 
made to take an adherent coat of silver. Silver 



76 Electro-plating, 

may be made to adhere to lead alloys with skil- 
ful treatment without this coat, but the work 
is done more easily and better when thus coated. 
The solution employed must be an alkaline one, 
as acid solutions, by their action on iron, steel, 
and zinc, undermine the deposit of copper and 
render it loose. The alkaline coppering solution 
is prepared by dissolving copper sulphate in hot 
rainwater in the proportion of 8 oz. of copper 
sulphate to 1 quart of water. When this has 
become cold enough, add first liquor ammonia to 
throw down the copper in the form of green mud, 
and then an extra quantity of ammonia to dis- 
solve this mud and convert the whole into a bright 
blue liquid. To this must be added a sufficient 
quantity of potassium cyanide solution to take 
all the blue colour out and make the solution 
amber-tinted, or the colour of old ale. It should 
then be left exposed to the air for twelve hours, 
then filtered through calico, and diluted with 
clean rainwater until each original quart is made 
up to one gallon of solution. This solution may 
be worked hot or cold, but gives a fine clear de- 
posit of copper when heated to 160° F. and w orked 
with current from a plating dynamo. Anodes of 
pure copper must be employed. 

When the articles of iron, steel, zinc, lead, 
pewter, and similar alloys, or those of brass with 
soft-soldered joints, are lightly coated with cop- 
per, they may be removed from the coppering 
bath to the alkaline mercury solution, and be 
there given a thin film of mercury, then rinsed 
and transferred to the silver-plating bath without 
delay. "Quicking," or coating with quicksilver, 
is done to secure the perfect adherence of the 
silver coating. The alkaline quicking solution 
is made by dissolving mercury slowly in dilute 
nitric acid, then adding enough strong solution of 
potassium cyanide to throw down the mercury in 
the form of black mud, and an extra quantity 



SiL VER-PLA TIKG. 7 7 

(with stirring) to dissolve this mud. Distilled 
water only must be used in making this solution, 
and it should contain 1 oz. of mercury in each 
gallon. Some free cyanide must also be added to 
act on the copper and ensure a bright film of 
mercur5^ Potassium cyanide is a most deadly 
poison, and should not be held in the naked hand. 

The acid solution of mercury proto-nitrate is 
employed and preferred by some platers. This 
is the first solution of mercury in nitric acid, 
largely diluted with distilled water. Its action is 
more speedy than that of the alkaline solution, 
but the film of mercury is not so thin and uniform 
as that from the latter. To prepare the mercury 
proto-nitrate solution, dissolve a few drops of 
mercury slowly in a mixture of equal parts nitric 
acid and distilled water, using only enough acid 
to dissolve all the mercury ; then dilute the whole 
to twenty times its bulk with distilled water. 
Swill the articles in this when they r.re ready for 
the plating bath, and then rinse in clean water. 

In professional plating, it is customary to 
weigh each article separately, or each group sepa- 
rately, to book the weights, and to determine the 
weight of silver to be deposited. In all plating, 
an estimate should be made of the surfaces in 
square inches, so that the anode surfaces and re- 
sistances may be adjusted so as to put on a tough 
coat of silver that will bear polishing and burnish- 
ing. This estimate must be based on experience 
with the silver solution in use ; but, as a com- 
mencement, allow two amperes to each 100 sq. in. 
of surface to be covered, and then find out by 
actual weighing what quantity of silver has been 
deposited in an hour. If this deposit is tough, 
adherent, and in good condition for polishing, the 
rate of deposit may be increased by lowering the 
resistance and using more current ; but this should 
be done gradually, until the highest rate of de- 
posit from the solution has been ascertained. The 



7 8 Electro-pla ting. 

rate, as indicated on the ammeter, will vary with 
the condition of the solution, the size of the anode 
surface, the distance of the anode plates from the 
articles, the voltage, and the character of the sur- 
face to be coated. A solution containing only one 
ounce of silver in the gallon will not yield good 
results except with feeble currents. If the anode 
surface is greatly in excess of the surface to be 
coated, the deposit will be rough and brittle, and 
a similar result may follow if the anode plates are 
too close to the articles. If the voltage is too 
high a similar result will be obtained, and if the 
articles have many sharp angles, edges, and 
points, these parts may take on a brittle coat of 
silver unless the current is kept low. If the 
anodes can be kept in motion whilst deposition 
is going on, or if both anodes and cathodes are 
kept moving, all the conditions previously men- 
tioned will be greatly modified, and the rate of 
deposition may be safely increased. 

The appearance of the silver coat whilst in the 
solution is a guide to its condition. The surface 
should momentarily change from grey to white 
and assume the whiteness of the anode plates in 
the course of two minutes. If it becomes more 
grey and bubbles arise from the slinging wire, the 
silver is going on too fast and the deposit is 
being '' burnt.'^ If it becomes brown it is still 
going on too fast. If it maintains a milky white- 
ness (a skim-milk white with a tinge of blue), it 
may be going on rather more slowly than is neces- 
sary. The rate of deposition may be regulated 
by moving the switch on the resistance board, 
and in a well-made silver-plating solution a de- 
posit of one ounce of silver per hour can be ob- 
tained with a current of eight amperes, two ounces 
with sixteen amperes, and so on. 

Deposition at the proper rate should be al- 
lowed to go on for from ten minutes to fifteen 
minutes, then each article should be taken out 



SlL VER - PL A TING. 7 9 

separately, rinsed in water, and scratch-brushed 
all over to test the adherence of the deposit and 
its condition. If this is satisfactory, the articles 
should be swilled in the potash and mercury dips, 
then rinsed and placed again in the plating bath 
until a sufficient time has elapsed to get the re- 
quired coat of silver on them. 

The silver-plating solution has been mentioned 
many times, but the method of preparing it has 
not yet been explained. This, however, will now 
be done. 

The best solution for silver-plating is the 
double cyanide of silver and potassium in distilled 
water. This salt may be made direct from pure 
silver plates or grains by first dissolving the metal 
in pure nitric acid diluted with distilled water, 
then evaporating all excess acid until silver nitrate 
crystals are obtained ; then dissolve these in dis- 
tilled water, and add a solution of potassium 
cyanide to form a curdy precipitate of the single 
cyanide, and finally dissolve this with a strong 
solution of potassium cyanide to form the double 
salt of silver and potassium. 

But, as the reduction of silver to its nitrate is 
tedious and noisome, pure silver nitrate is usually 
obtained from a druggist or drysalter. It is 
dissolved in distilled water, and then converted 
into the double cyanide of silver and potassium 
as above indicated. In doing this, to prevent 
waste of silver, care must be taken to avoid add- 
ing the cyanide solution in large quantities at a 
time. The precipitate must also be well stirred 
with a clean smooth stick of wood after each ad- 
dition of cyanide, and only enough of this added 
to throw down all the silver. When precipitation 
is complete, which is shown by all cloudiness dis- 
appearing from the liquid above the precipitate, 
the liquid must be carefully poured off and taken 
to the waste tub, and the precipitate of silver 
cyanide well washed by pouring clean water on it 



8o Electro-pla ting. 

several times, so as to agitate it well ; then drain 
it as dry as possible. To this wet mass of silver 
curds add a strong solution of the best potassium 
cyanide in distilled water, until all the curds have 
been dissolved. The quantity of cyanide in the 
solution should have been ascertained by weigh- 
ing the dry salt previous to its dissolution ; then 
add one- fifth in excess to provide enough free 
cyanide of potassium to dissolve the silver anodes 
in working and thus maintain the strength of the 
plating solution. The whole concentrated silver 
solution must next be filtered through well-washed 
calico, and added to the distilled water previously 
placed in the vat intended to contain the silver- 
plating solution ; it will then be ready for use. 

The amount of silver in solution needs a word 
of explanation. Although good silver-plating may 
be turned out of solutions varying considerably in 
strength, it is of great importance to the plater 
to know how much silver is contained in the solu- 
tion, and this may vary from 2 oz. to 6 oz. per gal. 
If grain or sheet silver is employed in preparing 
the solution, its strength may be easily ascer- 
tained ; but a little calculation is necessary when 
silver nitrate is used, for in every 170 oz. of silver 
nitrate there are only 108 oz. of silver. 

The method of preparing small quantities of 
silver-plating solution is as follows : Obtain 2 oz. 
of the best crystallised silver nitrate and dissolve 
it in 1 qt. of distilled water. Also obtain 2 oz. of 
best potassium cyanide and dissolve it in 1 pt. of 
distilled water. Add this a little at a time to the 
silver nitrate solution, and stir well each time with 
a glass rod until no white curdy precipitate is 
caused by the addition of a few drops. Allow the 
white curds to settle w^ell down, then pour off all 
the liquid. Pour on clean water, allow the curds 
to settle again, and repeat the process several 
times ; finally, drain off as much of the water as 
possible. Dissolve these white curds in a solution 



SiL VER -PL A TING. 8 1 

of potassium cyanide and add a little surplus to 
make it work freely. Use anode plates of pure 
silver, and work cold in a stoneware or glass 
vessel with current from two Smee cells, or from 
two or three Daniell cells. 

For making a large quantity (say 150 gal.) of 
silver-plating solution to contain 3 oz. of silver per 
gallon, 450 oz. of silver will be required. As there 
are 108 oz. of metallic silver in 170 oz. of silver 
nitrate, 45 lb. avoirdupois of silver nitrate will be 
required, and about 30 lb. or more of best grey 
potassium cyanide, to convert the silver nitrate 
into the double cyanide of silver and potassium. 
About 2.30 gal. of distilled water will also be re- 
quired. First well wash the plating vat and care- 
fully sponge out all dirty water, then half fill the vat 
with distilled water. Next half fill a large stone- 
ware or earthenware pan with distilled water and 
dissolve therein some of the silver nitrate in the 
proportion of 1 lb. of the silver salt to each gallon 
of water. Stir with a glass or clean wood rod 
until all the silver crystals are dissolved. Then 
dissolve some of the potassium cyanide in dis- 
tilled water, in the proportion of \ lb. to \ gal., 
and add this carefully, whilst stirring, to the silver 
nitrate solution as long as it causes white curds 
or clouds. Now allow to settle, carefully pour off 
all the water, and throw this away. Then pour on 
fresh spring water to wash the silver curds well, 
and pour all this water away. Next dissolve all 
the curds in a strong solution of potassium 
cyanide, and pour this solution into the plating 
vat through a calico filter. Proceed thus until 
all has been prepared and added to the first lot 
\w the plating vat. Then add 5 lb. more of potas- 
sium cyanide, previously dissolved, to form free 
cyanide. The voltage necessary to work this 
solution is from four to five volts. The current in 
amperes is in proportion to the surface of goods 
immersed in the solution at any one time, so may 



82 Electro-plating, 

range from 1 to 100 amperes. The safe rate is 
found by experience, and varies with the charac- 
ter of the work in hand. 

The plating sokition should be kept in good 
working order. Only distilled water should be 
allowed in it, and it should always be kept up 
to a certain mark and thus maintained at the same 
strength. No chemicals of any kind, except po- 
tassium cyanide, should be added to the solution, 
and this must be used cautiously. A certain 
quantity of free cyanide must always be present 
in the plating solution to dissolve the silver anodes 
at a rate equal to that of the silver deposited. 
Then the anodes are not coated with black slime, 
providing all other necessary conditions are ful- 
filled ; but a slimy condition of anodes may be 
due to an insufficiency of silver in the solution or 
to an accumulation of dirt. Too much free 
cyanide in the solution will be shown by a coarse 
crystalline condition of the anode surface and 
rapid erosion of the edges of the anode plates, 
which soon become ragged. In this solution the 
deposit is liable to become loose on copper, brass, 
and other metals readily dissolved in cyanide 
solutions. 

In making silver solutions, only the best potas- 
sium cyanide should be used ; this is sold under 
the name of best grey potassium, 99 per cent, 
cyanide. Inferior cyanide may be employed for 
pickling solutions ; but, because it contains a 
large percentage of uncombined potash salts, it 
should not be used in plating solutions, as these 
too soon become charged with an excess of potash 
salts, caused by a gradual withdrawal of cyanogen 
from the free potassium cyanide in solution. In 
process of time this excess of potash renders the 
old plating solution unfit for use, as shown by its 
muddy appearance, and by the rough character of 
the silver deposited from it. 

If the muddiness of the plating solution is 



Silver-plating, 83 

caused by dirt, filter the whole solution through 
good calico. This dirt may consist of dust from 
the workshop, carbon from the potassium cyanide, 
and finely divided silver from the anodes ; it 
should therefore be saved and put in with the 
waste rinsing water to recover the silver. 

All water suspected to contain silver should 
be saved and evaporated in an enamelled iron 
vessel, the resulting salt being mixed with waste 
sawdust and sold to a refiner. 

If a silver-plating bath is exposed to strong 
sunlight, a small portion of the free cyanide will 
absorb carbonic dioxide from the air and part 
with its cyanogen, and thus become converted into 
potassium carbonate. The loss of free cyanide 
may easily be made up by adding a small portion 
of potassium cyanide dissolved in distilled water. 
When silver-plating baths are not in use, they 
should be closely covered to prevent this loss, and 
to keep out dust. They should also be well stirred 
an hour or two before being used again. 

As the silver salts will creep up the sides of 
the vat, and thus find their way to the floor, it is 
necessary to wash them back into the vat with a 
little distilled water applied with a stout brush 
almost every day. An abundance of clean water 
must be provided for rinsing, and the rinsing 
waters must be frequently changed. Failure in 
securing an adherent deposit of silver may often 
be traced to the use of dirty rinsing waters. 

The anode plates, which serve the double pur- 
pose of conveying the current into the solution 
and also keeping up its strength, must be of pure 
annealed silver, and their surfaces should always 
slightly exceed the surfaces of all the articles 
immersed at any one time. If they fall short 
of this for any length of time the solution will 
become impoverished, and, on the other hand, if 
their surface is excessive, the solution may get 
too rich. They should be easily removable. 



84 Electro-plating, 

Standard silver must not be employed for the 
anodes, as it contains 1\ per cent, of copper. 
French silver coins contain even a higher per- 
centage of copper ; therefore coin silver must not 
be used at all, or the deposited silver will be hard 
and of a bad colour. The plates may be of any 
size and length suitable to the vat and work, but 
should not be less than \ in. in thickness. If kept 
moving whilst at work, the lower edges rapidly 
wear thin, and the plates should be reversed to 
wear both ends equally. This is also necessary if 
the plates remain stationary, as they are then 
liable to be cut through at tlie top of the solution. 

Anode plates are usually suspended from the 
anode rods by hooks of pure silver wire, holes 
being punched in the upper edges of the plates 
for this purpose. The anode rods may be kept in 
motion if they are made to hang on a steel frame 
moved to and fro by machinery. The frame should 
have broad steel rollers running on steel rails, and 
these must be connected to the positive pole of 
the dynamo. Steel is preferable to other metals 
because it is not readily corroded by potash salts 
or cyanide. 

Boxwood furnishes the best sawdust for drying 
silver-plated goods, as it does not contain dye, 
acid, or resin liable to stain pure silver. But if 
the sawdust is heated in a vessel by direct contact 
with flame, it will become charred, and in this 
condition will stain silver. The pan containing 
the sawdust should therefore always have a water 
or steam jacket. The goods may be dried thus in 
clean boxwood sawdust without spotting or tar- 
nishing, and, in this clean condition, arc more 
easily given a liigli finish. 

Some notes on silver-plating a fe\v particular 
articles will now be given. 

In silver-plating a cruet frame, if it is to be 
highly polished in every part, it will be necessary 
to disconnect the parts where they are soft-sol- 



SiL VER-PLA TING. 85 

dered, and polish each separately. But this is not 
usually done, as cruet frames thus soldered are of 
common quality, and best plating is not expected 
on them. In best quality cruet frames all parts 
are put together with screws, and by simply with- 
drawing these, every portion of the cruet can be 
got at with the polishing mops. The bases of some 
old cruet frames sent to be re-plated are often so 
pitted with corrosion as to render a smooth polish 
impossible. If they must be made like new, and 
there is no other method of doing this, it will be 
advisable to fill in the pits with solder ; then 
grind the whole level, and polish the surface 
before plating. This, and all parts coated with 
soft solder, must be coated with copper before 
they are silver-plated. Joints may be coated with 
copper by rubbing with wet copper sulphate and 
a bunch of fme iron wire. Large surfaces must 
be coppered in an alkaline coppering bath. 

It is not usual to silver-plate tinware, but 
when it is necessary, it must be cleaned by scour- 
ing with potash on a cotton mop ; it is then rinsed 
in a hot solution of potash, and coated with 
copper in an alkaline coppering solution before it 
is immersed in the silver-plating solution. Silver 
does not firmly adhere to tin, but will firmly 
adhere to copper ; hence the advisability of first 
coating the tin with a thin layer of copper. As 
tin is a very soft metal, it can be easily scratched, 
even with a soft cotton brush not quite free from 
dust and grit. If, therefore, a bright surface is 
desired on the lightly silvered tinware, this may 
only be rinsed in the hot potash without scouring, 
very lightly coppered in a good solution, trans- 
ferred promptly to the silvering vat and given only 
a thin coat of silver. 

Generally, pure tin, pure lead, and their alloys, 
irrespective of proportions, such as soft solder, 
pewter, and Britannia metal, are treated in a 
special manner in preparing them to receive an 



86 Electro-plating, 

electro-deposited coat of silver. When thoroughly 
cleaned and ready for plating, each article is 
swilled in a hot solution of potash and transferred 
at once, without rinsing, to the plating solution, 
where the deposit is struck by a vigorous current 
at first, but the current is reduced to finish the 
deposit slowly. Huch metals cannot be quicked 
in a mercury solution unless they have a coat of 
copper or of brass deposited on them previous to 
immersion in the solution. This is sometimes 
done, and is a safe method for novices in the art, 
but requires the same preparation as for silver- 
plating direct. All such metals should be lightly 
scratch-brushed and polished after they are coated 
with silver. 

For silvering the inside of a tin-plate teapot, 
well scour it with powdered Bath brick or Trent 
sand until quite bright ; then well rinse in potash 
water, and fill, whilst still wet, with a good alka- 
line coppering solution. Connect the teapot by a 
copper wire to the negative pole of the plating 
dynamo, and suspend a strip of copper in the pot 
by a wire connected to the positive pole, and see 
that this wire does not touch the vessel. In a few 
minutes the inside should be coated with a thin 
film of bright copper ; then pour out the coppering 
solution, and substitute a silver-plating solution, 
and a strip of silver instead of the copper strip. 
Deposit silver in the teapot until of the required 
thickness ; then pour out the silver solution, rinse 
with hot water, scratch with a soft wire brush, and 
polish lightly. 

For silver-plating a sword and sheath, two vats, 
each not less than 4 ft. long and 1 ft. 6 in. wide, 
will be necessary. Fill one with an alkaline 
coppering solution, and the other with the silver 
cyanide plating solution. The sword must be 
freed from grease, etc., by scouring in the potash 
pickle, then lightly coated with the alkaline cop- 
pering solution, rinsed in clean water, quicked in 



SiL VER - PLA TING. 8 7 

a cyanide of mercury solution, and lightly silvered 
in the silver-plating solution, then scratch-brushed 
and polished. The sheath must be treated in a 
similar manner, but care must be taken to remove 
first the wooden strips which form the lining. To 
do this, it will probably be necessary to take out 
a set screw in the collar, and remove this, then 
loosen the strips of wood with a knife and draw 
them out. A plug of wood should be put in the 
screw hole, and the head of the screw should only 
be lightly plated. Both sword and sheath must 
be slung horizontally in the baths, and the sheath 
should be given a heavier plating than the sword. 
The insides of tea-pots, coffee-pots, and similar 
vessels have often to be plated and to be in a 
bright and finished condition in every part. It is 
quite possible to reach the insides of ordinary 
vessels with suitable scratch-brushes, but there 
are always some interstices in ornamental and 
chased work that cannot possibly be reached by 
mechanical means, and it would never do to leave 
those parts with the dull white or "matt" coating 
left upon them when finished in an ordinary silver- 
plating solution. ' It is, therefore, usual to make 
up a special brightening solution to deposit a 
bright coat of silver on the finished article. The 
solution for bright plating is made up as follows : 
Take 1 pt. of old jiilver-plating (cyanide) solution, 
and add to it from 2 oz. to 3 oz. of bisulphide 
of carbon. Put this in a glass-stoppered bottle 
capable of holding \ gal. of liquid, and add 
to it 3 pt. more of the old plating solution ; then 
shake the bottle well for a few minutes, and set 
aside to rest for twenty-four hours or more. 
Carefully decant the bright liquid into another 
similar bottle without disturbing the sediment, 
and add from 2 oz. to 3 oz. of good cyanide of 
potassium dissolved in distilled water. Shake up 
the contents of the bottle to mix them, and when 
all is settled down again, the mixture will be fit 



88 Electro-plating. 

for use. The daily dose of this liquid to the 
bright-plating solution must only be in the pro- 
portion of 2 fluid oz. to each 20 gal. of solution. 
This should be added at the close of each day's 
work, and be well stirred into the plating solution. 
If too much brightening solution is added, the 
deposit will be brown, or marked with black or 
brown streaks, and the solution spoiled. It should 
never be added to the ordinary plating solutions, 
since they are apt to be spoiled for other work 
by the addition of the brightening solution. 

The work in course of brightening should be 
closely watched. The brightening effects will be- 
gin at the bottom of the article and spread up- 
wards ; when the article is covered, it should be 
removed at once, and quickly rinsed in warm 
water. As bisulphide of carbon is an evil-smell- 
ing, poisonous liquid, of a volatile nature, great 
care must be exercised in its use, so as not to 
breathe the foetid vapour, the odour of which re- 
sembles that of rotting cabbage. The worker is 
warned against sniffing at the bottle containing 
bisulphide of carbon or brightening solution. 

Some special instructions may be given on the 
treatment of the various little oddments that come 
to the country jeweller to be re-plated, such as 
alberts, charms, lockets, brooches, buckles, scarf- 
pins, rings, and one or two spoons or sugar-tongs. 
The small jeweller is not advised to imdertake 
the job of plating spoons and forks in dozens, or 
anything larger than a dessert spoon, as larger 
articles demand more room than can be found 
in the small vat of a working jeweller, and more 
anode surface than he has at his command ; but 
there is no reason why he should not profitably 
engage in the plating of small articles. If he 
does, he will find the following notes particularly 
useful. The preparation of the articles by boiling 
in alkali, rinsing, scratch-brushing, scouring, and 
quicking has already been described. Each article 



S/L VER - PL A TING . 8 9 

must be hung to a long hook made of copper wire, 
and suspended by this in the solution whilst re- 
ceiving its coat of silver. For very small articles 
this hook may be made of No. 28, whilst for larger 
articles it may be made of No. 20. This hook is 
made in the form of an S, the lower end hooking 
behind a pin, into a bow, into a link, or to some 
projecting part of the trinket. The articles should 
be wired with wet hands before the final dips, and 
not touched with the hands afterwards, but placed 
straight away into the plating solution, suspended 
to the cathode rod attached to the zinc of the 
battery. Two or three cells in series will be 
enough to force current through the wires arid 
deposit the silver in good condition. The articles 
should be coated white with silver within a few 
minutes of placing them in the depositing vat. 
They should then be taken out and brushed with 
a clean scratch-brush in clean water, to test the 
adherence of the deposit. If this does not strip, 
the article must be rinsed in clean water, and 
restored to the vat to receive a finish coat. The 
time taken to do this will depend upon the price 
to be paid for plating, since a longer time in the 
vat represents a thicker coat of silver. By care- 
fully weighing the article after it is polished, pre- 
paratory to plating, and weighing again when 
dried, after it has been plated, the weight of 
silver deposited upon it can be found. A thick 
coat of good adherent silver may be deposited in 
two hours ; but the time taken will always depend 
upon the condition of battery and solution. It may 
be said that for sixpence a trinket only a mere 
blush of silver over and above the scratch-brush 
coat can be allowed, and this may be laid on in a 
few minutes. 



90 



CHAPTER V. 

Copper-plating. 

Copper is a highly malleable, ductile, and ten- 
aceous red metal very largely used in the industrial 
arts. It does not resist the action of acids, and 
even moisture affects it, causing it to form an 
oxide known as verdigris ; this, under the action 
of carbonic acid, turns to green copper carbonate. 
Copper is also caused to oxidise by heat ; it is 
volatile only at a great heat. It has a specific 
gravity of 8-9, and melts at 2,000° F. Commercial 
copper contains many impurities, amongst them 
being iron, silver, bismuth, antimony, arsenic, 
cuprous oxide, lead, tin, and sulphur. Copper is 
much used in its commercially pure state, but is 
greatly in demand as the chief ingredient of the 
important brass and bronze alloys. 

The metals on which a coat of copper is de- 
posited by electricity are lead and its alloys ; tin 
and its alloys ; iron, tinned iron ; zinc ; and steel. 
When articles made of these metals are to be 
silver-plated, nickel-plated, or gilded, it is al- 
ways advisable and sometimes necessary pre- 
viously to coat them with copper. This cannot 
be done in a copper sulphate solution, because 
the acid in this dissolves the metals. 

The merits and demerits of copper-plating as 
part of a preparatory process to nickel-plating for 
cycle work may be discussed briefly. Skilful 
hands, old in the trade and experienced, ridicule 
the idea of having to coat with copper before 
putting on a coat of nickel. An experienced hand 
can deposit nickel direct on iron and steel, and 
the nickel will adhere firmly, but the novice is 



COPPER-PLA TING. 9 T 

advised first to copper all steel and iron parts of 
cycles, and thus save himself much after-trouble. 
The reason for this lies in the fact that copper will 
adhere to iron and steel more firmly than nickel 
does, and nickel will adhere firmly to copper. 
Another point in favour of copper-plating is, that 
it enables tlie plater to see whether the articles 
are perfectly clean or not, for copper will not de- 
posit firmly on dirty iron or steel, and the coat 
strips off (when subjected to scratch-brushing) 
from all dirty patches. The nickel deposit can 
also be better seen on copper than on iron, and 
the progress of the depositing process watched. 
Copper will also enter into fine pinholes and 
cracks, and stop them, whilst nickel goes on 
around such spots, and leaves them open to the 
action of damp. A coat of copper, then, after the 
work has been scoured, is recommended, and this 
coat should be well scratch-brushed, dipped in the 
cyanide dip, and rinsed before placing the article 
in the nickel-plating solution. If a special job 
is in hand, a thick coat of copper should be de- 
posited, and this well burnished all over tg make 
sure of perfect adherence, then scoured to give 
a slight roughness to the burnished surface. A 
coat of brass will do quite as well as copper if 
a good brassing solution happens to be available. 
When articles are badly pitted with deep rust- 
spots and scale from forgings, or castings have 
their surfaces full of small sand-holes, this pre- 
vious coppering process enables the plater to fill 
in all such defects with solder, get a smooth sur- 
face on the defective spots, and coat the whole 
with copper. The best way of soldering such pits 
is by means of a chloride of zinc flux, applied with 
a spoon of copper wire which is always left in the 
flux, and thus contaminates it with a little chloride 
of copper. A slight film of copper is thus de- 
posited on iron and steel, to which the solder 
adheres perfectly. This patching must be done 



92 Electro-plating, 

before the articles are polished, in order that the 
patches may be made quite smooth before placing 
them in the coppering solution. Articles thus 
patched must not be left long in the potash-vat, 
because this alkali will dissolve solder readily, al- 
though it has no action on iron. 

Only a thin film of copper is necessary to form 
a basis for the deposit of nickel. When this has 
been obtained uniformly all over the article, re- 
move it from the coppering solution, and test its 
adherence with the brass wire scratch-brush lubri- 
cated with water. If the copper comes off from 
any part, give the faulty spot a good scouring 
with whiting ; rinse well in clean water, and give 
the whole article an extra coat of copper, placing 
one of the anodes near the fault, so as to cover 
it at once with copper. If the coat of copper is 
good and perfect, rinse it well in clean water, and 
place the article at once in the nickel-plating 
solution, unless it has been determined to burnish 
the coat. If the coat has been burnished, give the 
article a dip in the cyanide solution, to remove 
any tarnish caused by the action of the air ; then 
rinse it, and place it in the nickel solution. 

Although copper can be easily deposited from 
an alkaline solution, it requires some amount of 
skill to deposit the metal in a tough condition fit 
for burnishing. 

Various solutions have been used for copper- 
plating ; but the most successful one is made as 
explained on p. 76 of the previous chapter. Its 
usual proportions are : Copper sulphate, 4 oz. ; 
potassium cyanide, 12 oz. ; liquid ammonia, 4 oz. ; 
rainwater, 4 gal. Distilled water may be used 
instead of rainwater, but spring and river waters 
are not suitable because of the earthy matters 
held by them. The solution should be held in an 
enamelled iron vessel. 

The following is a typical copper-plating solu- 
tion : Dissolve 1 lb. of copper sulphate in \ gal. 



Copper-plating. 93 

of rainwater, then stir in enough liquor ammonia 
to throw down the copper in the form of a green 
precipitate, and dissolve this to make a blue 
liquid. Dilute this with an equal bulk of rain- 
water, then add sufficient potassium cyanide to 
destroy the blue tint and produce the colour of 
old ale. Filter the whole through calico and ex- 
pose to the action of air for twenty-four hours, 
when it should be ready for use. Work it cold or 
hot. 

Enough free cyanide should be present in the 
coppering solution to dissolve the copper anodes 
easily, but an excess of free cyanide should be 
avoided when the tension of the current is high, 
and the copper solution is impoverished. It is 
necessary to add some good cyanide of potassium 
to the solution from time to time, as found neces- 
sary, to keep up the supply of free cyanide ; but 
as cyanide itself does not freely dissolve the oxide 
of copper formed on the anodes, a little liquor 
ammonia also should be added occasionally to 
assist the action of the cyanide. This is prefer- 
able to a large excess of free cyanide in the solu- 
tion. 

Anode plates of pure copper must be em- 
ployed ; these are connected by No. 16 s.w.G. 
copper wire to the positive pole of the generator. 
If the plates do not dissolve freely, but become 
encrusted with a green slime, a small quantity 
of potassium cyanide and of liquid ammonia 
should be added to the solution. The best electro- 
deposited pure copper should be selected for 
anode plates. Discarded Daniell battery-plates 
will serve the purpose very well. All other condi- 
tions being equal, employ an anode surface slightly 
in excess of that uf the articles being plated. 
The rate of deposit can be regulated by exposing 
more or less anode surface. Too little anode sur- 
face may result in a hard, dark deposit of copper, 
if the tension of the current is high. Too much 



94 Electro-plating, 

anode surface may result in a loose, soft deposit 
of copper, which will peel off when scratch- 
brushed. This may be remedied by altering the 
resistance board, and interposing a higher resist- 
ance in circuit. Too much anode surface tends 
to make the solution rich in copper, and this con- 
dition also favours a rapid deposit, which may be 
loose under certain other conditions, such as too 
much free cyanide and too much current. On the 
other hand, too little anode surface tends to an 
impoverishment of the solution, and consequent 
hard, dark, and unequal deposits of metal. Un- 
favourable conditions may be remedied by moving 
the articles nearer to or farther from the anodes, 
in addition to the means already proposed. 

If the solution is kept supplied with free 
cyanide and free ammonia it may be worked with 
a current at from 6 to 8 volts ; but the deposit may 
be improved by heating the solution to from 150° 
F. to 170° F., and the vat may then be worked at 
from 4 to 6 volts. The best generator is a plating 
dynamo, the next a three-cell accumulator ; and 
among primary batteries the next best would be 
four \ gal. Bunsen cells. 

The surfaces of all articles to be copper-plated 
must be cleaned and prepared. Iron and steel 
articles may be cleaned from rust by steeping and 
swilling in a pickle composed of 6 fluid oz. of sul- 
phuric acid and \ oz. of muriatic acid in each gal- 
lon of water. They must then be rinsed in clean 
water and immersed in a pickle composed of \ lb. 
of American potash dissolved in each gallon of 
hot water. If the surfaces have been pitted, the 
corroded parts must be polished with emery held 
on a mop in a polishing lathe, after which the 
articles must be well swilled in the hot potash 
pickle to free them from oil or grease. All sur- 
faces must be w^ell polished before the copper is 
deposited, because the thin coat will not permit, 
much polishing afterwards. 



Copper-plating. 95 

Articles made of lead and tin, or their alloys, 
must be first scoured with sand and water, using 
a hard brush for the purpose, to free them from 
oxide ; then rinsed in the hot potash pickle ; again 
scoured with finer sand to polish them ; wired 
with short lengths of No. 24 s.w.G. soft copper 
wire ; again rinsed in the hot potash pickle, and 
transferred direct to the plating vat. The potash 
pickle will prevent rust forming on iron and steel 
articles, and will clear oxide from lead and tin 
and their alloys ; but it is advisable to transfer 
the articles quickly to the plating vat, and not to 
rinse them in water on the way. 

Zinc articles are cleansed in a similar manner ; 
but very fine sand or finely powdered bath brick 
must be used in scouring. If articles are bright 
and free from rust and tarnish, only a light brush- 
ing with a vegetable fibre brush in the potash 
pickle will be necessary to prepare them. 

The actual process of copper-plating will now 
be described. Each article must be attached to a 
short length of copper wire, which suspends it 
in the vat. Use No. 24 s.w.G. for small articles, 
and No 18 s.w.G. for heavy ones. Each article 
should be held by the slinging wire during the 
final rinse, and the free end of this wire is bent 
over a brass rod on the plating vat, attached to 
the negative pole of the generator. Move each 
article to and fro with a rinsing movement when 
placing it in the vat, to remove any air bubbles 
on the surface. The current should be regulated 
by a resistance, usually a long length of German 
silver wire furnished with a switch. The re- 
sistance can also be increased by diminishing the 
surface of the anode exposed to the plating solu- 
tion, and by placing the anode further from the 
article being plated. If the current is too strong, 
the deposited copper will be dark in colour and 
loose in character, and this will also happen if 
the solution contains too much copper. Move- 



96 Electro-plating. 

merit of the articles whilst being plated will assist 
in securing a bright and smooth deposit. Some 
gas is given off from the articles whilst deposition 
is going on, but this should be regulated by ad- 
justing the current. Only a few minutes is re- 
quired for plating each article. 

The plated articles should be rinsed in plenty 
of clean water to free them from cyanide and 
copper salts. If the surface is to remain coppery, 
the article should be rinsed in hot water, placed 
at once in hot bran or hot sawdust, and moved 
about in it until quite dry and bright. Pure 
copper readily tarnishes in the air when damp, 
but may be brightened with a scratch-brush. 

If the surface is to be nickel-plated, the articles 
must be rinsed and transferred at once to the 
nickel-plating vat. If a thicker deposit of copper 
is desired, use an electrotyping solution, after de- 
positing a thin film of copper in the alkaline solu- 
tion above mentioned. If the plated articles are 
to be gilded, get a very thin and bright deposit 
of copper, or brighten it with a scratch-brush ; 
then rinse and transfer at once to the gilding vat. 
If they are to be silver-plated, coat with a thin 
film of mercury before placing them in the silver- 
plating solution ; give a brisk swill in the quicking 
solution (p. 76), and then rinse in clean water. 

For copper-plating sheet lead, first scour the 
lead plates clean with sand and water, then 
briskly rinse them in a solution of pearlash (1 lb. 
to the gallon), and transfer from this direct to the 
copper-plating solution without handling or pre- 
vious rinsing in water. Use a current at from 
6 to 8 volts. If the first deposit is coarse and 
loose, remove the plates and well brush them in 
water with a hard fibre brush, again rinse in the 
potash or pearlash solution, and return to the 
copper-plating bath, using a reduced anode sur- 
face, or keep the plates moving whilst being 
plated. In this way a bright facing of copper may 



Copper -pla ting, 9 7 

be obtained, which must be well rinsed and dried 
quickly to prevent tarnishing. Electro-deposited 
copper rapidly tarnishes in air when damp. 

Occasionally, a piece of carbon has to be 
copper-plated for the purpose of soldering some- 
thing to it. The coppering is easily done by the 
following process: Dissolve copper sulphate in 
warm water until the water will not dissolve any 
more. Place this copper solution in a large 
battery jar, or similar stoneware vessel, and select 
a porous battery jar to stand up in the centre. 
In the porous pot place a rod or plate of amal- 
gamated zinc in a solution of sulphuric acid (1 
part acid to 12 parts water), and suspend the 
carbons from a wire attached to this zinc with 
their ends only dipping in the copper solution. 
See that the ends to be coppered are quite clean 
and specially free from grease. In the course 
of half an hour enough copper will be electro-de- 
posited on the carbons to take a coat of solder. 
Rinse each in hot water, and do the soldering 
whilst the copper is new. 

A special bath for copper-plating iron has been 
recommended as under, but it is not thought to 
have any advantage over the alkaline bath al- 
ready given. For use cold, the bath is made of 
bisulphate of soda and cyanide of potassium, 18 oz. 
each, carbonate of soda 36 oz., acetate of copper 

17 oz., liquid ammonia 12^ oz., and water 5^ gal. 
If the bath is to be used warm, make it as follows : 
Bisulphate of soda 7 oz., cyanide of potassium 
25 oz., carbonate of soda and acetate of copper 

18 oz. each, ammonia 10 oz., and water 5^ gal. 

So that copper can be electro-deposited on 
terra-cotta, earthenware, etc., the surface of these 
materials must be first rendered conductive to 
electricity. This is done by coating with black- 
lead, bronze powder, or some other finely divided 
metal. Blacklead is brushed into the pores of the 
material in a dry condition until the whole sur- 



98 Elect R o-pla ting. 

face is evenly coated and well polished. Bronze 
powders are mixed with methylated spirit and 
applied in the form of a paste. If the surface 
is briskly brushed with a new brass-wire brush, 
it wdll become coated with brass and thus made 
conductive. A copper wire must then be tightly 
twisted around some part of the article and con- 
nected to the conductive surface by a liberal ap- 
plication of the powder. Thus prepared, the 
article is immersed in an electrotype solution, con- 
nected to a battery or dynamo, and copper de- 
posited in the usual manner. Only a very thin 
coat must be applied if the pattern is to be re- 
tained or smoothness is desired. If the surface 
of a flat object is only covered, this coating may 
be afterwards peeled off ; but if the object is sur- 
rounded with copper, as a vase or statue, the coat 
w^U be adherent. 

In depositing a copper coating on a plaster 
statue, coat the statue several times with linseed 
oil or saturate with melted stearin to render the 
plaster non-absorbent to the copper salts ; these 
would destroy the statue. When the surface is 
dry and firm, apply a coat of paint made of bronze 
powder mixed with methylated spirit only. Work 
this into every crevice with a soft brush, and when 
it is dry well brush every part w^ith blacklead to 
get a smooth surface. Brush w^ith an alcoholic 
solution of phosphorus, and then with an ammo- 
niate solution of silver, prepared by dissolving 
silver nitrate to saturation in strong ammonia. 
To ensure conduction to all parts of the statue, 
several fine wires should be led to the deeper 
crevices. A battery of Daniell cells should be 
used, and deposition should proceed slowly to ob- 
tain a smooth coat of copper. 

The carved work, relief decorations, and other 
enrichments of w^ooden doors, etc., may by electro- 
plating be given a coat of copper, brass, nickel, 
or other metal that will in certain circumstances 



Copper-plating. 99 

have a very rich appearance. Before plating, the 
wood is preserved and prevented warping by being 
coated with a good linseed oil varnish. When it 
is varnished, metal strips as conductors are 
fixed around the edges, and the whole surface is 
rendered conductive by blackleading. A big 
plating vat is required, and the operation of de- 
positing the metal is carried out as usual. The 
excellent fire-resisting qualities of a wooden door 
covered with tinplate are recognised, the metal 
preventing the wood taking fire and the wood 
framing preventing the door warping from the 
heat and allowing flames to pass though, this last 
being a defect of doors made wholly of iron. A 
tinplate covered door has a poor appearance, how- 
ever, and is suitable only for workshops and ware- 
houses. An electrically deposited coat of metal 
serves the same purpose as the tinplate, and the 
process is suitable for doors in all situations. 

The copper-plating of aluminium has many 
difficulties. This metal cannot be nickel-plated, 
as nickel must be deposited in an alkaline bath, 
using ammonia and the salt ammonium sulphate, 
and all alkaline salts rapidly corrode and dis- 
solve aluminium. So before nickel can be de- 
posited, the aluminium must be copper-plated, 
and even this method is very troublesome, since 
the small ingress of gas or a slight development of 
hydrogen at the cathode, though very feeble and 
perhaps scarcely visible to the naked eye, will be 
a hindrance to the setting of the deposit. But if 
a salt solution is used, the acid part of this will 
not dissolve the aluminium, but it will oxidise any 
hydrogen developed during operation in the 
nascent state. The salt solution recommended is 
nitrate of copper, whose effect can be further en- 
hanced by using an excess of nitric acid. A solu- 
tion of 100 grammes of sulphate of copper and 60 
cubic centimetres of concentrated nitric acid of 
specific gravity 1-3334 per 32 oz. of solution is 



I oo Electro-pla ting. 

recommended. The aluminium must be first 
roughened, preferably by sand-blasting (although 
it may be roughened by rubbing with emery), and 
then dipped in a weak solution of caustic soda or 
potash until a considerable gassing takes place. 
Next wash in concentrated nitric acid and place 
in a copper bath. The copper anode should have 
about the same surface as that of the article being 
coppered. Constant moving either of the article 
or solution is essential. Use current at a pressure 
of about 4 volts, with a distance between the 
electrodes of about 2 in. The opening and closing 
of the circuit is made by dipping in and taking 
out the objects. The length of time taken in 
coppering will be from ten to twenty minutes. 
Too thick deposits will strip off. When the sur- 
face has been coppered, the article can be covered 
with nickel in the usual way (see Chapter VII.). 

The best method of plating aluminium is the 
mechanical, not the electrical, one. The mechani- 
cal method consists of laying over it a sheet of 
clean nickel, fastening the two closely together, 
and placing them between two large cast-iron 
blocks previously heated to a dark red, a pressure 
of 6^ tons to the square inch beng exerted on the 
blocks, this pressure being applied gradually and 
sustained for about fifteen minutes. The sweated 
plate can now be rolled as an ordinary plate. 



lOl 



CHAPTER VI. 

GOLD-PLATING. 

Gold may easily be deposited in good condition 
on a large variety of metals and alloys from a 
solution of the double cyanide of gold and potas- 
sium. This may be made and kept warm in an 
enamelled iron saucepan over the flame of a gas- 
burner or of an oil lamp, the saucepan serving as 
the vat. One cell of any of the many suitable 
varieties may be used, even one dry cell being 
suitable. It is only necessary, therefore, to get 
such a cell, and some gold solution heated to a 
temperature of 160° F. in a saucepan, to connect 
the trinket to be gilded by a length of No. 24 
s.w.G. copper wire to the negative (zinc) pole of 
the cell, and a strip of pure gold by a similar length 
of wire to the positive (copper or carbon) pole of 
the battery, and then to suspend both trinket and 
gold in the hot solution for a few moments to coat 
the trinket with gold. 

A country jeweller often recognises the advan- 
tage of the possession of a small plating outfit, if 
only in the saving of time required in sending the 
job to be done in town. Now, nearly all firms 
supplying electro-platers' outfits and materials 
for electro-platers also supply as a speciality a 
small outfit suitable to the wants of watchmakers, 
opticians, country jewellers, etc. The following 
lists are selected from two catalogues, and these 
will show the materials in general use for the pur- 
pose. Canning and Co. supply the following: 
One gilding vessel and portable stand complete ; 
i gal. rich gold solution ; one Bunsen burner and 
tube; two 7-in. rectangular Bunsen batteries; 



1 02 Electro-PL A ting, 

1 pt. sulphuric acid, or one tin of Canning's B or 
negative battery powder ; 2 pt. nitric acid, or 
one tin of Canning's A or positive battery powder ; 
one sawdust pan and boxwood sawdust ; one plate 
brush ; I lb. best rouge ; 1 lb. mercury ; one amal- 
gamating brush; 1 lb. No. 22 b.w.g. copper wire, 
for connections ; two hand scratch-brushes. For a 
silver-plating plant they supply extra: one 1-gal. 
enamelled vessel ; 1 gal. of rich concentrated 
silver solution ; two rods, 10 in. long and | in. in 
diameter ; two connectors for the ^-in. rods. If 
a coppering plant is also required, they supply an 
extra enamelled iron vessel and 1 gal. of copper 
solution, together w^ith the necessary connecting 
rods. It may be stated as a commentary on this 
list, that the Bunsen battery charged with nitric 
acid emits most acrid noxious fumes, and should 
be kept in an outside shed or in a cupboard ven- 
tilated into a chimney with a good up draught. 
Covered bell wires of No. 20 s.w.G. may be em- 
ployed as conductors from the battery to the 
plating vats. The Bunsen cells may also be 
charged with other excitants which do not emit 
such noxious fumes. The zinc elements in a Bun- 
sen battery whilst at work must be kept coated 
with mercury, which, w4th a suitable brush to 
apply it, is also provided. If the jeweller has not 
a lathe which can be utilised, he should obtain 
a combined scratch-brush and polishing lathe, with 
assorted finishing mops and brushes. 

J. E. Hartley and Sons supply the following 
small outfits : Gilding outfit Q : — Enamelled iron 
gilding vessel, with tripod stand and Bunsen burner 
as shown by Fig. 61 ; one 6-in. Bunsen battery ; 
1 qt. gold solution ; gold anode ; 6 ft. of connecting 
wire ; and one hand sci atch-brush. Gilding outfit 
II : — Enamelled iron gilding vessel, tripod stand 
and burner ; one 8-in. Bunsen battery ; 1 gal. gold 
solution ; gold anode ; 6 ft. of connecting wire ; 
one hand scratch-brush of fine wire, and one of 



Gold-PL A ting. 



103 



medium wire. They also supply an optician's and 
watchmaker's outfit, which comprises an enamelled 
iron vessel (with stand) for the gilding solution as 
above ; 1 qt. gold solution and gold anode ; also 
suitable vessels for silver and for copper, with 

1 gal. of silver solution and 1 gal. of copper solu- 
tion, together with silver and copper anodes ; 
also three 6-in. Bunsen batteries, 10 ft. of covered 
connecting wires ; wire for slings ; three hand 
scratch-brushes ; three assorted scouring brushes ; 

2 lb. pumice ; and 2 lb. whiting. 

In a regular plating shop, the gilding vats are 




Fi"-. 61.— Small Gildinpf Outfit. 



generally of enamelled iron, mounted in iron 
frames furnished with iron legs and heated with 
Bunsen burners, as in the model outfits above 
enumerated. In large establishments rectangular 
vats hold from 10 to 30 gal. of gold solution, and 
are fitted with steam jackets, as it is prejudicial 
to health to have the vats heated by gas jets, 
and with the use of the steam jackets the tempera- 
ture of the solutions can be regulated better. 

The preparation of articles to be electro-gilded 
is much the same as for those to be coated with 
silver, with a few exceptions. It is not necessary 
first to coat bright iron and steel with copper, 
as gold may be firmly deposited in a hot solution 
of the double cyanide of gold and potassium. But 



104 Electro-plating, 

it is advisable to copper-plate articles of zinc, 
lead, pewter, and other soft alloys before they are 
electro-gilded, because gold goes on them loosely. 
Copper, silver, brass, German silver, and similar 
hard metals with their alloys form suitable 
materials for articles to be gilded. Gilding metal, 
a kind of gunmetal, and the various kinds of brass 
which are sold under grand names for sham 
jew^ellery, all form excellent bases on which to 
deposit gold, taking a very fine polish in their 
preparation. The articles should alw^ays be highly 
polished before they are gilded, this greatly affect- 
ing the nature of the surface after gilding. 

One method of producing a matt or frosted 
appearance on gilded articles is to make the sur- 
face rough by means of frosting brushes, by the 
sand blast, or by the action of acid, before the 
article is gilded. 

It is not necessary in gold-plating to coat the 
surface with meroury before gold is deposited on 
it, except in the case when a very thick deposit 
is required on bare copper. 

The gilding solution can be made in one of 
three w^ays. 

(a) The best and the one chiefly used by pro- 
fessional platers is composed of the double cyanide 
of gold and potassium in distilled water. The 
single cyanide of gold is a very light yellow 
powder, 223 gr. containing 197 gr. of gold. This 
is added to a strong solution of potassium cyanide 
and stirred until dissolved, then made up to the 
required strength with distilled water. The 
strength varies from 5 gr. to 15 dwt. of gold in 
the gallon, the richer quality being used where 
large ciuantities of heavy gilding are done each 
day, and the poor solution for merely blushing 
the surfaces of trinkets w^ith a gold tint. 

(6) The solution may be made by dissolving gold 
direct into a heated solution of potassium cyanide, 
and passing an electric current through the solu- 



GOLD-PLA TING. 1 05 

tion from one strip of gold to another until 
sufficient of the metal has been acquired. This 
method is the most economical for small opera- 
tions, but as the solution thus made contains an 
excess of potash, it is not to be recommended for 
large operations. 

(c) The solution may also be made by the 
chemical method in a laboratory attached to the 
workshop if the necessary skill is available, but 
not otherwise, as unskilled attempts at making 
cjanide of gold usually result in much loss of gold. 
By the chemical method, the gold salt is precipi- 
tated from its solution of gold terehloride by 
cautiously adding a weak solution of potassium 
cyanide ; the resulting yellow powder is well 
washed, and then dissolved in a strong solution of 
pctassium cyanide to form the gilding solution. 
But, as the signs of complete precipitation are 
not w^ell defined, and as the single cyanide of gold 
is so easily dissolved in a very slight excess of 
potassium cyanide, there is danger of great loss 
of gold in the making of the gilding solution by 
this method. 

Gold-plating solutions are generally heated for 
use, and the repeated heating drives off the sol- 
vent property of the solution ; consequently, gas 
having a noxious odour is given off, cyanogen 
(prussic acid gas) is separated from the potas- 
sium cyanide, and leaves potash alone in the 
solution. As potash alone will not dissolve gold, 
more of this precious metal is withdraw^n from the 
solution than is dissolved from the gold strip 
(anode) to make up the loss. As a consequence, 
the gilding becomes more and more poor in colour, 
because the strength of the solvent has diminshed, 
and the quantity of gold in the solution has also 
decreased. Experienced electro-gilders add a 
small quantity of potassium cyanide occasionally 
to make up this loss, and also regulate the surface 
of gold anode to the work in hand so as to prevent 



io6 Electro-plating. 

impoverishment of the solution. The addition of 
cyanide to a gilding sohition must be made care- 
fully to avoid a great excess, as this will spoil 
the colour of the gilding, giving it a foxy-brown 
tint. 

Pure gold (fine gold) must be employed in 
making gilding solutions and for the anodes. 
Coin gold and standard, or sterling, gold, 
being alloys of gold with copper or silver, 
should not be employed. If silver is present 
in the gilding solution, the deposit will be 
of a pale tint, grading to a greenish yellow with 
each increase of silver. If copper is present in 
the solution, the deposit will have a ruddy tint, 
deepening to a reddish brown, and then to a dark 
bronze with an increase of copper. The effect of 
copper in deepening the tint of gold deposits has 
been used in fancy jewellery, slight additions of 
the inferior metal being made to the gilding bath 
from time to time, and small copper anodes em- 
ployed to secure ruddy tmts in the gilding ; but 
solutions thus alloyed require more skill to work 
them successfully than those made of pure gold, 
and are always more or less uncertain in their 
action. The proportion of copper to gold is not 
determined by the proportions of these metals in 
the solutions and in the anodes, but by the selec- 
tive power of the current working the solution. 
As this varies with the resistance of the circuit, 
which alters with each variation in temperature 
and change of metal to be gilded, so does the 
proportion of the two metals, and the consequent 
colour of the deposit. 

The solution (6) described briefly on p. 104 is 
recommended as being the cheapest and best for 
the amateur gilder and the jeweller in a small 
way of business. To prepare it, get 1 pt. 
of distilled water, and \ lb. of best 95 per 
cent, cyanide of potassium. The latter is a deadly 
poison, and will injure health even if handled with 



Gold-plating. 107 

the naked hand; it should be kept locked-up in 
a wide-mouthed glass-stoppered bottle. Dissolve 
2 oz. of the potassium cyanide in one pint of hot 
distilled water, and place it in the vessel in- 
tended to serve as a vat. Get two strips or plates 
of pure gold, weighing from 7 to 10 dwt. each; 
punch a small hole in the upper edge of each, and 
hang each strip on a hook made of No. 20 platinum 
wire. Hang one strip in the vat connected to 
the wire leading from one pole of the battery (say, 
the zinc plate), and the other strip of gold to the 
wire leading from the other pole. See that the 
gold dips only deep enough in the cyanide solution 
just to touch the platinum hooks, but do not allow 
the copper wires to hang in the solution. Copper 
and gold will dissolve in cyanide solutions, but 
platinum will not dissolve in them. The gold is to 
be dissolved to make up a gilding solution, but 
copper is not desired in the solution. If all has 
been done right, an electric current will pass from 
the zinc plates in the battery to the copper plates, 
and from these along the wire to the gold strip in 
the cyanide solution, through this, and back to 
the battery by way of the other gold strip and the 
wire leading to the zinc plate, thus completing 
the electrical circuit. Whilst current is passing in 
this w^ay, gold will be dissolved off from the strip 
of gold hanging to the wire leading from the 
copper of the battery, and will be taken up by the 
cyanide of potassium to form the double cyanide 
of gold and potassium solution. Keep the solution 
heated up to 160° F., and keep the battery con- 
nected to it for one or two hours. At the end of 
this time hang a German silver wire for a moment 
or tw^o in the vat, connected to the wdre leading 
from the zinc of the battery. If the wire takes 
on a coat of a satisfactory character, hang both 
strips of gold to the opposite wire, and call them 
gold anodes, and connect the work to be gilded to 
the cathode wire — that is, the wire from the zinc 



1 08 Elrctro-pla ting. 

o£ the battery. The action of the battery may bo 
carried on until 5 dwt. of gold has been dis- 
solved into the solution, or gilding may be begun 
with only 1 dwt. of gold to the pint of solution. 
The quantity of gold in the solution can always 
be increased if the surface of the articles to be 
gilded is less than the surface of the anodes, and 
there is an excess of cyanide in the solution. The 
contrary condition will result, of course, in an 
impoverishment of the solution. A solution rich 
in gold deposits a rich-looking coat of gold in a 
short time, whilst one poor in gold works slowly, 
and deposits a poor-looking coat. 

A full battery of at least three Wollaston, 
Smee, or Daniell cells, or two Bunsen cells, should 
be used in making the gilding solution, but it can 
be worked afterwards with a battery of one cell. 
The Gassner or the Leclanche are both unsuitable 
to use in making up the solution, but may be used 
ia working it after it has been made up. 

Gilding solution prepared by the chemical 
method (see c, p. 105) will be found inferior to that 
produced by method &, for though it will deposit 
a coat of gold of a fairly good colour, the coat is 
apt to strip off whilst being polished or burnished. 
A further objection is the loss of gold involved. 
This solution is best made up to the strength of 
8 dwt. to thd gallon. To make it, proceed as 
follows : Take 8 dwt. of fine gold and put it in a 
porcelain dish of about 40 oz. capacity — an 
enamelled saucepan will do if the dish is not 
attainable — then pour upon this, gently, about 
4 oz. of aqua regia, which is a mixture of 2 parts 
of hydrochloric acid and 1 part of nitric acid. 
Another aqua regia composition is 3 parts pure 
hydrochloric acid, 1 part pure nitric acid, and 1 
part distilled water. Gently heat the vessel con- 
taining the gold and aqua regia over a Bunsen 
burner to accelerate the chemical action, and when 
the gold is dissolved, pour the resultant solution 



Gold-PL A ting, i 09 

of chloride of gold into another vessel and evapo- 
rate the acid. If too much heat is used the gold 
will be reduced to the metallic state ; if this should 
be the case, add a little more aqua regia to re- 
dissolve, and then re-evaporate. When the acid 
has been driven off, add to the resultant chloride 
of gold about one pint of distilled water, or failing 
this, use water that has been vigorously boiled and 
filtered. If, when the chloride of gold is added to 
the water, a white precipitate is formed, the chlo- 
ride of gold solution should be carefully decanted ; 
this precipitate is chloride of silver, which should 
never, on any account, be allowed to get into the 
gilding solution. To the solution of chloride of 
gold, a strong solution of cyanide of potassium 
should be added (this need not be of any specific 
strength) ; a brown precipitate of cyanide of gold 
is produced. The solution of cyanide should be 
carefully added, so that a drop at last should 
have no effect upon the clear solution. Too much 
cyanide will re-dissolve the cyanide of gold. Allow 
the solution to stand for about fifteen minutes, 
pour the clear liquor off, and wash the precipitate 
two or three times with distilled water. For this 
purpose, a quantity of distilled w^ater is poured 
upon the precipitate ; this is then allowed to settle 
and the water run off ; this is done two or three 
times. When the cyanide of gold is sufficiently 
washed, a solution of strong cyanide of potassium 
is added to dissolve it. To the solution thus pro- 
duced, some more of the cyanide of potassium 
solution is added to form free cyanide. Then add 
sufficient distilled water to make up to one gallon. 
This solution must be worked with a pure gold 
anode, and a battery power of two Bunsens or 
their equivalent, holding about a pint and a half 
each. If the solution works a bit slowly, add a 
little fresh cyanide. The solution must be worked 
at a temperature of 125° to 135° F. A solution of 
the same strength as above, and worked at a 



no Electro-plating. 

temperature of 132° F. with two quart Bunsens, 
has produced work of first-class colour, far better 
than with other heats and strengths of solutions 
and currents. 

There is a number of other baths that may be 
used, but those already given are the ones in 
common employment. The following four baths 
require the addition of one gallon of distilled 
water, and are used hot. For use wdth iron and 
steel, take bisulphite of soda, 2 oz. ; crystals of 
phosphate of soda, 8 oz. ; pure potassium cyanide, 
\ dr. ; gold chloride, 160 gr. Dissolve the phos- 
phate of soda in a portion of the water heated. 
In another portion of the water dissolve the bi- 
sulphite and potassium cyanide, and in the re- 
mainder of the water dissolve the gold chloride. 
Stir the latter slowly into the phosphate solution 
when cold, and then add the bisulphite and 
cyanide solution. The bath should be heated to 
about 180° F. A strong current is required. 

For bronze and brass the following has been 
used : Bisulphite of soda, \\ oz. ; crystals of phos- 
phate of soda, 6^ oz. ; bicarbonate of potash, | oz. ; 
caustic soda, | oz. ; pure potassium cyanide, \ oz. ; 
gold chloride, \ oz. Dissolve all, except the gold 
chloride, in hot water. Then filter, and, when 
cool, stir in the gold chloride, dissolved in water. 
The bath should be heated to about 130° F. 

A bath, which is simple in preparation, but 
which cannot be recommended owing to the want 
of uniformity in the results obtained, is made as 
follow^s : Potassium cyanide, 3 oz. (nearly) ; gold 
chloride, 1 oz. Dissolve the chloride in the gallon 
of water mentioned above, and then stir in the 
cyanide. 

The following bath is for silver or copper 
or similar alloys: Bisulphite of soda, 1^ oz. ; 
crystals of phosphate of soda, 9^ oz. ; pure cyanide 
of potassium, \ oz. ; gold chloride, 160 gr. This is 
prepared in the same way as the bath for iron and 



GOLD-PLA TING. 1 1 1 

steel. The vessels containing the bath should be 
of glass, porcelain, or enamelled iron. Before 
electro-gilding lead, zinc, or tin articles, it is best 
to give them a coat of silver. A bichromate bat- 
tery is preferable when using these hot baths. 

Roseleur's cold gilding solution is made up of 
fine gold, 10 parts ; cyanide of potassium, 30 parts ; 
liquid ammonia, 50 parts ; distilled water, 1,000 
parts. The gold is converted into the terchloride 
of gold, and this is dissolved in distilled water. 
The liquid ammonia is added to this, and ful- 
minating gold is thrown down as a brown pre- 
cipitate. This precipitate is washed on a paper 
filter, and dissolved at once with the cyanide of 
potassium solution. The water is now added, and 
the solution boiled for an hour to drive off excess 
of ammonia. Care must be taken in making this 
solution not to dry any of the precipitate, as it is 
a dangerously explosive substance. 

Another cold gold-plating bath is made with 
pure potassium cyanide, 3^ oz. ; gold chloride, 
3| oz. Dissolve the cyanide in part of the water 
and the gold chloride in the remainder of the 
water. Then add the latter solution to the first. 
This solution should be boiled for about half an 
hour before use. 

Several attempts have been made, but without 
success, to invent a cheap electro-gilding solution 
for metal jewellery. Much, however, may be done 
with copper anodes ; these may be so worked in 
the ordinary gold cyanide solution as slightly to 
alloy the deposit of gold with copper, and thus give 
a pleasing blush to a thin film of the precious 
metal. The cheapest method of preparing these 
solutions is to dissolve pure sheet gold in a solu- 
tion of potassium cyanide by means of current 
from a battery until a test sample receives a nice 
blush of gold in a few moments' treatment. The 
articles must be clean and well polished, lightly 
scratch-brushed, strung on wires attached to the 



1 1 2 Electro-pla ting. 

negative pole of the battery, and dipped for a 
few moments in the gilding solution ; then rinsed 
in clean hot water, and brushed with a scratch- 
brush of very fine, soft wire. 

Alloyed gold may be deposited from an alloyed 
solution of the double cyanide of gold and potas- 
sium, but the process is not easily managed, and 
the deposit not always certain. The following pro- 
cess has been recommended : Dissolve 8 dwt. of 
gold alloy in each gallon of solution containing 
4 oz. of commercially pure cyanide by the usual 
battery process. Work the solution at a tempera- 
ture of from 160° to 170° F., using the alloyed 
anodes. If the colour is too dark, reduce the 
density of the current. The colour of this alloyed 
gilding has been found to A^ary with each slight 
variation in current density brought about by a 
different size of anode or of article being gilded, 
or of slinging wire employed, or by a change in 
the temperature of the solution. 

Enough has now been said on the preparation 
of the solution. 

Fine soft copper wire should be employed to 
connect the articles with the cathode rod of the 
gilding vat, and the lengths of wire thus used are 
named slinging wires. These may be inserted in 
any holes in the articles, or twined round any 
obscure projections, or formed into slings for the 
suspension of coins and medals. In gilding some 
patterns of long thin chains it is advisable to take 
the chain in loops, and insert the wire in several 
links, and if the chain is a bad conductor it will 
be necessary to twine it around the slinging wire. 
If this is not done, there will be patches of links 
imperfectly gilded, or left ungilded. 

Gold anodes should be made of pure gold plate 
or ribbon, not less than -^V in. in thickness. Thin 
gold leaf or sheet is apt to become ragged at the 
edges as the anode gets worn ; these ragged edges 
droD tiny pieces of gold to the bottom of the 



GOLD-PLAT/NG. II3 

bath, and thus the solution, or the gilded goods, 
gets credited with an undue portion of the wasted 
anode. Plates of pure gold y^^ in. in thickness 
can be easily bent over a platinum wire, and this 
forms the best support for the anode, since it is 
not acted upon at all by the gilding solution or 
its fumes. Copper, silver, or brass wires dissolve 
and contaminate the solution with an alloy. If 
alloyed gold is used for the anodes, the deposited 
metal will soon become an alloy of gold instead 
of pure gold ; and the alloy is as likely to be as 
variable in composition as most deposited alloys 
are, and thus give trouble to the gilder. If gold 
anodes have been hardened by hammering, they 
should be annealed before being used. As a rule, 
the surface of anode presented to the solution 
should be slightly in excess of the surface to be 
coated with gold. As anodes are more quickly 
worn away at the surface of the solution, because 
of the action of the air on them, they should })o 
lil"ted out when not in work, and their position 
frequently changed. 

The green slime on a gold anode when in a 
plating solution is caused })y an insufficiency of 
free cyanide in the solution in proportion to tlio 
other ingredients and the current employed. Tlie 
green slime may indicate a deficiency in gold 
(;yanide, and in this case much careful building up 
of the solution will be necessary whilst small 
quantities of cyanide are added. It may indicate 
excess of current for the work in hand or a larger 
anode surface than is necessary. Exhausted and 
over-w^orked gold solutions are frequently indicated 
by green slime on the anodes. 

It might be supposed that because the gilding 
solutions in general use are made with pure gold, 
and because the anode plates also are of pure gold, 
that the metal deposited would also be pure, and 
of the same colour as the original gold. But this 
is not always the case. 



1 1 4 Electro-pla ting. 

A newly made solution of the double cyanide of 
gold and potassium invariably deposits a lemon- 
tinted gold when worked under ordinary con- 
ditions. As the solution ages, its deposit darkens, 
until it resembles heavily alloyed gold. This 
darkening is sometimes due to an accumulation 
of copper dissolved from the slinging wires, and 
from the articles that have been gilded in the 
solution ; but it may occur in solutions that have 
been carefully protected, and is then due to im- 
purities contained in the added potassium cyanide, 
and to an accumulation of free potash in the solu- 
tion. 

The working temperature of an electro-gilding 
solution ranges from 120° to 180° F. Within this 
variation the temperature greatly affects the 
colour of the deposit. Below 120° F. a pale 
brassy-coloured deposit is obtained ; from 120° F. 
upwards the colour improves until 160° F. is 
reached ; then, as the internal resistance of the 
bath is reduced, the gold goes on faster, and the 
colour darkens. 

Gold in good condition can be deposited with 
a very feeble current, even from one cell of the 
simplest battery. A very good deposit can be ob- 
tained from a rich solution working at \ volt, 
with only a fraction of an ampere. If the solution 
has but a small quantity of gold in it, the deposit 
will be very pale, but may be darkened by in- 
creasing the voltage. If the solution is in good 
condition, this darkening disappears in scratch- 
brushing the deposit, but does not disappear if 
the deposit is foxy, as w^hen deposited from a de- 
fective solution. Gold deposited fast, w4th a high 
current density, soon assumes a brown tint, and 
much of it is in a loose powdery condition ; but 
the brown appearance can be removed by brushing 
the surface. 

Gold can be deposited in good condition from 
very weak solutions if attention be paid to their 



Gold-PL A ting. ~ 115 

temperature and to the current. With only a few 
grams of gold per gallon of solution, a good colour 
can be obtained when worked at a temperature 
of 160° F. and from 1 to 2 volts. As the quantity 
of gold per gallon is increased, the resistance of 
the solution decreases, and gold is deposited 
faster with the same voltage. This alters the 
colour, though not to any great extent, in newly 
made solutions ; in fact, the colour indications 
may deceive the w^orker, for heavy deposits at low 
pressure from a rich solution may be very pale, 
and thin deposits of a high colour may be obtained 
from attenuated solutions worked at from 5 to 7 
volts. As the density of the solution increases 
owing to the accumulation of potash and im- 
purities, the colour of the deposited gold becomes 
darker, and this high colour is permanent. 

When a cyanide of gold solution is being pre- 
pared, the worker adds a quantity of potassium 
cyanide more than is required to dissolve the gold 
cyanide, and this excess is named "free cyanide.'' 
It dissolves the pure gold anode, and thus feeds 
the solution with gold. If this is deficient, the de- 
posit will soon become pale, and have an im- 
poverished appearance. If it is excessive, the 
colour of the deposit will be too high, and a great 
excess will cause it to assume a foxy-brown tint, 
which will be permanent, and not removable by 
brushing. 

When the electric current is too strong, a sil- 
ver-plating solution deposits its metal in the form 
of a dirty grey loose powder, or the coat may have 
the appearance of pewter. This is called " burn- 
ing'' the work. When gold is deposited under 
similar conditions, the deposit may vary in appear- 
ance between a loose brown powder to a foxy red, 
and from this to a dark bronze, resembling in 
colour that of a dirty penny. Brown deposits of 
gold may be improved by a judicious use of colour- 
ing mixtures, but those of a foxy red and bronze 



ii6 Electro-plating. 

tint are usually intractable, and the workman will 
find that they can only be restored by freshly 
cleaning and re-gilding the article. As " burning '' 
is caused by too great a density of current de- 
livered at a high voltage, it may be avoided by 
using a resistance board in circuit with the vat, 
and throwing in sufficient resistance to stop back 
the excess volume of current. 

A very dark brown deposit of gold from an 
electro-gilding bath may also be due to excessive 
free cyanide and to a deficiency of gold in the 
solution. This may be remedied by dissolving 
more gold in the bath, or by adding cyanide of 
gold until the excess cyanide of potassium has 
been taken up. 

The condition of the surface to be gilded affects 
the colour of the gold deposited upon it. On bare 
copper, the deposit has a nuldy tint ; on a bare 
silver surface, all tliin deposits of gold have a pale 
tint, the thinnest having a greenish-yellow hue. 
Nickel and German silver surfaces impart a warm 
tint to thin deposits of gold. Pale brass gives a 
pale tint ; but brasses and bronzes containing 
higher percentages of copper, such as gilding 
metal, impart a warm tint to thin deposits of gold. 
A rough and dull copper surface w^ill impart a 
foxy-brown hue to thin deposits, whereas, if the 
same copper article has its surface highly polished, 
the deposit will have a warm, bright tint. 

A matt or frosted surface on silver imparts a 
pleasing yellow tint to a thin deposit of gold if 
the minute silver points are clean and bright. 
Another effect may be produced by depositing a 
thin layer of gold on freshly deposited copper, 
and still another by depositing gold on a thin 
layer of freshly deposited silver. When the colour 
is affected by the condition of surface, gold de- 
posits are rarely improved by scratch-brushing. 

When gold solutions are alloyed with copper or 
with silver, an alloyed deposit results ; but its 



\ 



GOLD-PLA TING. I I 7 

colour cannot be predetermined by employing 
anode plates of the desired alloy. The deposited 
alloy does not always contain the same propor- 
tions of the mixed metals as the anode plates. 
This is due to the varying rates of deposit of the 
metals employed. Pleasing effects may be ob- 
tained by adding a small quantity of copper to a 
gold solution, when a peculiar ruddy tint is im- 
parted to the gold deposit. Various pale shades 
may also be obtained from a gold solution alloyed 
with silver, a greenish deposit being thus ob- 
tainable. Such gilding solutions are not suitable 
for ordinary gilding work, and cannot be after- 
w^ards restored to their former pure condition. 

For gold-plating in colours there must be a 
separate bath for each separate colour. For 
green gilding add silver-plating solution to the 
gilding solution in very small quantities at a time 
until the required tint has been obtained ; too 
much silver solution will cause a whitish deposit, 
known as white gold. To gild red, add a solu- 
tion of copper cyanide, or use a copper anode 
until the desired colour is deposited. To gild rose 
pink, first gild the article and scratch-brush it, 
then deposit a mere flash of silver on the surface ; 
on this deposit a mere tint of copper from an 
alkaline copper bath, and then just a blusli of gold 
l<> tint the copper. The process is a delicate one. 

A thick deposit of gold is obtained in the fol- 
lowing manner: The articles are frequently taken 
from the gilding bath and scratch-brushed to re- 
move the brownish appearance, then rinsed and 
returned to the bath. If this is not done the gold 
will not adhere, but will simply surround th^e 
article in the form of brown mud, and this con- 
dition is soon observed when the solution is poor, 
and when the current is too strong. 

Highly polished small steel articles, free from 
grease and oil, may be gilded in an electro-gilding 
solution of gold cyanide. When a quantity of 



1 1 8 Electro-pla tixg. 

such articles is to be gilded, they may be done in 
dozens at a time if suspended in the solution in a 
basket of platinum gauze ; this basket must be 
shaken whilst the gilding process is going on. 
Any gold deposited on the platinum may be after- 
wards dissolved off in the gilding solution without 
doing it any injury. The steel articles are scratch- 
brushed and polished in the usual manner. 

Articles made of aluminium cannot be gilded 
direct in a solution of the double cyanide of gold 
and potassium, because the alkali therein attacks 
and rapidly dissolves the aluminium. They should 
therefore be first coated with copper in a solu- 
tion of copper sulphate, and then transferred to 
the gilding bath. 

The insides of mugs, spoons, salt cellars, etc., 
are gilded by means of a special arrangement 
in which the articles are connected to the cathode 
system ; then they are filled with gilding solution, 
and gold is deposited from a gold anode held in 
the solution by hand. If the vessel will hold any 
gold solution, fill it and connect it with the nega- 
tive pole of the battery or dynamo, and for an 
anode use a strip of gold on the end of a wire con- 
nected to the positive pole. The anode is held 
in the gilding solution contained in the vessel, or 
moved about in it as required. If the vessel will 
not hold liquid, it may be gilded with a rag mop 
wrapped around the anode and repeatedly dipped 
in the gilding solution, connection being made 
with the battery as before. 

The scratch-brushes used in brushing gilded 
work are made with very fine brass wire, some 
being crimped for extra elasticity combined with 
softness. Special shapes are required for such 
goods as rings and watch cases, so that the in- 
sides may be brushed and polished. Sometimes a 
good brushing with a scratch-brush is all the 
finish required for the insides of goods. When 
chains are heavily gilt, each link must be twisted 



Gold- PL A ting. i i 9 

around and brushed, whilst only a short length 
of chain is held between the fingers and thumbs of 
both hands. 

Gilt articles are polished on soft mops made 
of swansdown, soft felt, and chamois leather, 
using finest rouge composition as the polishing 
material. The insides of rings are polished on 
felt fingers so tapered as to fit any size of ring. 
Chains are polished on broad-shaped bobs covered 
with soft leather on the convex sides. Thimbles 
and similar hollow ware have specially formed 
bobs made with wooden stocks of the required 
shape covered with fine soft felt. 

Contrasts in the various grades of finish are 
sometimes resorted to for effect. A frosted ap- 
pearance is secured by using a coarse scratch- 
brush having long bunches sparsely set in the 
boss, and holding a stick to the revolving brush 
just before it strikes the gilded articles. Raised 
parts are burnished with suitable burnishers made 
of steel, bloodstone, and agate. A final yellow 
blush is often imparted by a momentary dip in a 
new gilding solution, after which the article is 
rinsed in hot water and dried. 

Gold is deposited rapidly from ordinary electro- 
gilding solutions, and a sujQ&ciently strong coat 
may be deposited in the course of a few minutes, 
the rate being about 37 gr. an hour per 
ampere. Weigh the articles after they have been 
cleaned and after they have been gilded to ascer- 
tain the quantity of gold on them. When, there- 
fore, by calculation of time and current, it has 
been estimated that enough gold is deposited, the 
article must be rinsed in clean water, scratch- 
brushed to remove the brown appearance, dried 
by rubbing in sawdust or otherwise, and then 
weighed. If there is not enough gold on the 
article, return it to the gilding bath. 

Professionally, the weight of gold and silver 
deposited is according to the charge to be made 



120 Electro-PL A T/XG. 

for the job. The article should therefore be 
weighed in a balance when it has been dry-finished 
for plating, and the weight entered in a book. 
If it is a ring, for instance, weighing 50 gr., 
and the price will allow of 2 gr. of gold being 
put on, it is immersed in the gilding solution for 
a few minutes, then rinsed, scratch-brushed, and 
dried, and again weighed. If it weighs 51 gr., 
it must be again put into the gilding solution for 
a few minutes, and the foregoing process repeated 
until it weighs 52 gr. The price per grain is 
easily ascertained by dividing the price of pure 
gold per ounce by 480, the number of grains in an 
ounce. Silver is reckoned by the pennyweight, 
taking ^ dwt. as the lowest fraction. To the cost 
of metal must be added the cost of labour in pre- 
paring and finishing, and a small addition to cover 
the cost of deposition. This gives the prime cost. 

In gilding lockets, light brooches, and similar 
light trinkets, the solution will get inside and re- 
main there during the process of scratch-brushing. 
This must be taken into consideration when weigh- 
ing the goods, and care must be taken to have 
them dry. Some of the hollow ware is filled with 
a waxy composition which oozes out in the course 
of gilding, and this falsifies the calculations made 
to determine the deposit of gold. 

The anuitcur and small professional plater are 
interested more in the gilding of such trinkets as 
brooches, chains, coins, rings, etc., than in larger 
and more ambitious work ; so it is proposed here 
to treat this branch of the gilder's art in greater 
detail. A brass ring could be taken from a man's 
finger, and, seeing that it is bright and clean, a 
person might conclude it would not need cleaning 
before hanging it in the gilding bath. Assume it 
to be merely wiped with a scrap of rag, a bit of 
copper wire tied to it, and hung in the gilding 
bath. In a few moments it receives a coat of gold 
all over, and nij^y be rinsed in warm water to free 



GOLD-PLA TING. 121 

it from the cyanide salts, wiped dry with a rag, 
and handed back to the owner, gilded. The ring 
looks fairly well, but by rubbing it with the palm 
of the hand the very thin coat of gold can be 
removed in a few moments, leaving the brass bare. 
All trinkets may be thinly gilt in a similar manner, 
and the thin coat of gold can be as easily rubbed 
off. If the ring is left in the gold bath for a few 
minutes, it will take on a brown coat instead of a 
golden tint. This brown coat is merely the matt 
appearance assumed by electro-deposited gold, 
and this will entirely disappear on brushing the 
coat with a brush of fine brass wire kept lubri- 
cated with stale beer. But on brushing in this 
way an imperfectly cleaned ring as it comes from 
a person's finger, the ring assumes a brassy ap- 
pearance, because the gold w^ent on loosely over 
the sweaty parts of the ring, and these loose par- 
ticles of gold are readily detached from the im- 
perfectly cleaned spots by the wire brush, and 
this non-adherence of electro-deposited coats be- 
comes more apparent with thick coats than with 
thin ones. To get a perfectly adherent coat of 
electro-deposited metal, the article must be 
thoroughly cleaned. Let it appear to be ever so 
clean to the eye, it must have contracted a trace 
of animal grease, or sweat, if it has been handled 
or worn, and this film of animal matter must bo 
taken off in a solution of strong alkali, such as 
soda, potash, or ammonia, before a coat of ad- 
herent metal can be deposited on the article. A 
strong solution of washing soda may be used if 
nothing better can be obtained. Pearlash is a 
better cleanser ; American pearlash, or potash, is 
still stronger ; and the best cleansers (in general 
use by professional platers) are commercial caustic 
soda and caustic potash. A piece of either of 
these, about the size of a walnut, dissolved in half 
a pint of hot water, will be enough to clean a 
dozen or two of small trinkets or chains. First 



12 2 ElECTRO-PLA ting. 

dissolve the potash or soda in liot water, then 
string a few trinkets on about 6 in. of No. 20 or 
Xo. 22 copper wire, and swill the bunch for a few 
minutes in the hot liquor. Transfer from the hot 
caustic solution to some clean warm water, and 
well rinse the trinkets in this to clear off the 
loosened grease. When the caustic liquid is cool, 
put it in a closely stoppered bottle to exclude the 
air, and thus preserve it for future use. After the 
grease has been loosened, if there is no corrosion 
on the article, it must be briskly brushed with a 
little whiting, or prepared chalk, or finely pow- 
dered pumice, again rinsed, and then hung in the 
gilding solution. 

If the trinkets are corroded, the corrosion 
must be removed in a pickle made of two parts 
sulphuric acid, two parts water, and one part 
nitric acid, after which the articles must be rinsed 
in clean water. 

Chains of a strong pattern may be rolled up 
in a mass between the two hands with a little 
whiting, and rubbed until polished ; but those of 
more delicate construction may not be treated in 
this way, but must be carefully brushed. Filigree 
work will require very careful treatment in clean- 
ing, and the gold should be deposited on it with 
low battery power, to prevent browning the de- 
posit, since it cannot be well brushed bright after- 
wards. Long chains of a delicate pattern should 
be threaded on a long thin copper wire passed 
through the links at intervals of from 2 in. to 3 in., 
or the wire should be wound spirally around the 
chain, to assist in conducting the current to all 
parts equally. 

Ear-rings and brooch pendants made of metal 
beads strung on silk should be suspended in a 
small basket of platinum gauze, in order that the 
beads may be placed in connection with a conduc- 
tor of electricity, since silk will not conduct the 
electric current. Such goods should not be put 



Gold-PL A ting. i 2 3 

in the caustic solution, as this will dissolve silk, 
and cause the beads to drop off. All trinkets 
containing hair, photos, and other material likely 
to be injured by the hot gilding solution, must 
not be put in the caustic solution until the hair, 
photo, etc., has been removed. It is also ad- 
visable to remove glass and stones liable to injury 
from this cause, and to re-set them when the work 
is finished. Trinkets made of aluminium only will 
not receive a coat of gold, but will dissolve in 
caustic solution and in the gilding solution (see 
p. 118). The brush used in brushing articles before 
gilding may be an old, but clean, tooth-brush, or 
any clean brush with stiff bristles. 

Special care must be taken with common jewel- 
lery. Bits of coloured glass, called " stones, ^^ are 
inserted in cheap brooches, rings, etc., under the 
names of rubies, diamonds, pearls, etc. In the 
commonest goods these stones are merely attached 
with gum or some soluble cement, which is dis- 
solved in the solution, and thus the stones come 
off. An examination of the goods before gilding 
will soon detect these, and, if the '' stones '^ are 
not held firmly in claws, they should be taken out 
by steeping the articles in hot water before they 
are prepared for gilding. They must be re-set 
after the goods are gilded. 

Whilst preparing the trinkets, the condition of 
their surface must be noted. If this is scratched, 
dented, bruised, or pitted with corrosion, the 
marks cannot be obliterated h^^ polishing and bur- 
nishing after gilding. All such blemishes must be 
removed before the articles are cleaned, if they 
are to be removed at all, and this can only be 
done by hand, either by pressing out the dents 
with suitable pieces of wood, or removing the 
scratches with a fine file and burnishing the filed 
spot. All repairs must be done first, as it will 
be difficult to repair electro-gilt goods when 
finished. 



124 'El EC TRO-PL A TING. 

Joints made with soft solder are difficult to coat 
with gold, but small joints may be doctored up 
by rubbing over them a wet piece of bluestone 
(sulphate of copper) and then touching the place 
with a piece of bright iron or steel. Both the 
iron and the joint will take on a coat of copper 
and cover the solder. Einse the joint in clean 
water, and hang the article in the gilding solution. 

If there are several soldered joints or much soft 
solder about the trinket, or if it is desired to coat 
a pewter medal, lead casting, zinc ornament, piece 
of tinned iron, or article composed wholly or 
partly of iron, tin, lead, or zinc, it is advisable first 
to coat it with copper in an alkaline coppering 
solution, made up as described on p. 76. At 
least three battery cells will be needed to deposit 
copper from this solution, and perhaps four cells, 
arranged in series, may be required to force the 
copper on a soldered joint ; but the copper thus 
deposited will be firm and adherent, and may be 
well polished. Use a piece of good copper, such 
as electrotype copper, as an anode. A mere film 
of copper is all that is required to protect the 
.irticle from the action of the gilding solution. 
If the film does not go on evenly in a few minutes, 
take the article out of the bath, briskly brusli 
it with a brass wire brush, and return it to tlie 
coppering solution. TJiis solution may be worked 
cold or hot, as may be desired ; but the deposit 
is brighter from a hot solution than from a cold 
one. This solution is also useful to give an 
18-carat gold appearance to gilded or pure gold 
goods. This is done by merely flashing a film 
of copper over the surface when finished, then 
flashing a film of gold on this, rinsing at once in 
hot water, and drying off in clean sawdust. By 
careful working in this way, a clever workman can 
get any desired tint of gold on the surface. 



125 



CHAPTER VII. 

NICKEL-PLATING AND CYCLE-PLATING. 

To facilitate tlie reader's mastery of the informa- 
tion about to be presented, it may be said that 
this chapter conforms to the following arrange- 
^ment: The nickel-plater's and cycle-plater's 
plant ; the necessary solutions ; the preparation of 
the work ; the preliminary coppering of cycle 
parts ; the actual process of nickel-plating ; the 
finishing of nickel-plated work ; re-plating ; the 
working of nickel-plating solutions in general ; 
and special applications of nickel-plating. 

In tlie cycle trade large firms have a plating 
sliop as a branch of their business ; but small 
repairers are content to send their work to pro- 
fessional platers, thougli, as business increases, 
they naturally wish to do all the work on their own 
premises, and so save time and intermediate 
profits. To this end they seek to do the plating 
at home, and they look about them for the in- 
formation necessary to guide them in laying dow^n 
a plating plant. This chapter is intended as an 
aid to tradesmen desirous of expanding their busi- 
ness in this way, but the information given will 
be of value to all who are interested in electro- 
plating. 

The cycle maker's nickel and copper plating 
outfit, supplied by Messrs. J. E. Hartley & Son of 
Birmingham, at £44, includes the following ap- 
pliances and materials: — 

Shunt-wound dynamo (4^ volts, 40 amperes, 
3^ in. pulley, speed, 1,700 revolutions per 
minute). 



12 6 Electro-pla tixg. 

Resistance board for regulating current. 
Plating vat (6 ft. by 2 ft. by 1 ft. 6 in.), 
lead-lined, burnt joints, bolted and match- 
boarded. 

Salts for making 100 gal, of nickel solution. 
Twelve nickel anodes (total weight 31 lb.) 
and hooks. 

Cable, three rods, five connections, and 
copper wire. 

Wrought-iron, potash, and hot-water tanks 
— the latter galvanised. 

Galvanised wrought-iron sawdust pan. 
Lead-lined scouring trough and twelve 
assorted scouring brushes. 

28 lb. of potash, bag of boxwood sawdust, 
and 28 lb. of pumice powder. 
A dynamo of 5 volts and 80 amperes, the pulley 
diameter being 3^ in. and the speed 1,100 revolu- 
tions per minute, is supplied in the place of the 
dynamo mentioned above at an extra cost of £6. 

To the above plant must be added the following 
items, costing £ll, if coppering is to be under- 
taken : — 

Resistance board. 
Vat, 4ft. by 2 ft. by 1 ft. 6 in. 
Chemicals for making 50 gal. of copper 
solution. 

Four copper anodes and hooks. 
Three rods and connections. 
Twaddell hydrometer. 
Five pounds of cyanide of potassium. 
The output of such a plant (with the larger 
dynamo) if under the control of an efficient plater 
is estimated at 100 sets of cycle fittings per w^eek. 
A nickel-plating outfit suitable for repairers, 
etc., is priced at £36; it has an output of 40 sets 
of cycle fittings per week, and differs from the 
£44 nickeling plant already specified in having 
a vat measuring 4 ft. by 2 ft. by 1 ft. 6 in., eight 
anodes, and smaller quantities of chemicals and 



Nickel-plating and Cycle-plating. 127 

materials, no coppering appliances and materials 
being included. 

Similar outfits are supplied by other makers, 
whose lists should be obtained. 

The above will be found sufficient for those 
who have facilities for preparing and polishing the 
cycle fittings, })ut if unprovided with a good pol- 
ishing lathe and its accessories, the cost of this 
must be added, since nothing can be well done 
without it. 

If a battery of large Bunsen cells is employed 
instead of a small dynamo, the total cost will be 
a few pounds less ; but a battery is not advised if 
power can be obtained for driving the dynamos. 
Batteries are messy, and the daily work of keep- 
ing them in order is something considerable, whilst 
the cost of their maintenance is a very serious 
item. To compete with professional platers, it is 
necessary to have polishing lathes driven by 
steam, water, gas, or some similar power, and the 
same source of power can be used for driving the 
dynamos. 

Directions are sometimes given for making 
nickel-plating solution by dissolving grain nickel 
in acid. As these home-made salts are inferior to 
those obtainable from a good dealer in nickel- 
plating outfits, and the quality of a nickel deposit 
largely depends on the purity of the salts used in 
making the solution, intending platers are advised 
to purchase the salt direct, instead of attempt- 
ing to make it in the workshop. 

The salt of nickel in general use for making 
nickel-plating solutions is the double sulphate 
of nickel and ammonia. This is a beautiful clear 
sea-green salt when pure, and takes the form of 
crystals, ranging in size from that of peas to that 
of chestnuts. The salt is merely dissolved in 
boiling water in the proportion of 1 lb. to each gal- 
lon, and poured into the vat when cool. Fairly 
good solutions may be made with 12 oz. of nickel 



128 Electro-plating. 

salt to the gallon ; but weak solutions offer a 
high resistance to the current, and the deposit 
is liable to be powdery and loose. Rainwater is 
preferable to spring-water in making the solution, 
and it is advisable to pass it through a calico 
filter into the vat, to remove any loose dirt acci- 
dentally acquired by the nickel salt. If best 
nickel salt is used, it will not be necessary to add 
either ammonia or table salt, these being em- 
ployed to correct some fault in old and poor 
solutions. 

If for some special reason it is desired to make 
the. double salt of nickel and ammonia at home, 
proceed as follows: Take of nickel 14 oz., dis- 
solve it in a mixture of three parts of strong 
nitric acid, one part of strong sulphuric acid, and 
four parts water. When dissolved, which is in- 
dicated by the fumes (caused by chemical action) 
ceasing, add a little liot water and filter ; the deep 
green liquid obtained is a strong solution of nickel 
sulphate. Then make up a strong solution of 
ammonium sulphate l)y dissolving 4 lb. of the salt 
in a gallon of water. For preparing the plating 
solution mix about half of ammonium sulphate 
solution witli the sulphate of nickel, and make up 
with water to one gallon. 

In working nickel solutions, they become too 
acid when insufficient anode surface has been pro- 
vided. To correct this excess acidity, add liquor 
ammonia in small quantities until the solution 
ceases to redden blue litmus paper. When a solu- 
tion ceases to deposit white nickel, a very small 
quantity of common salt is added, say \ oz. to the 
gallon of solution. 

Messrs. Hartley point out that if the nickel 
solution be weak, it offers too much resistance to 
the flow of the current ; whilst if it is too acid, 
the deposit is pulverulent and peels off. The 
brilliant whiteness of American nickel plating is 
due mainly to the quality and purity of the salts 



NtCKEL-PLATING AND CyCLE-PLaTING, tZQ 

used. A slightly acid bath is best for iron, this 
giving a beautiful white deposit, whereas an alka- 
line or neutral solution gives a darker shade. A 
yellow sediment in the plating solution is due to 
the bath being too alkaline. 

Litmus paper for testing the solution should be 
kept handy ; an acid solution turns blue litmus 
to red ; an alkaline solution turns red litmus to 
blue. The use of cast nickel anodes soon causes 
a bath to become alkaline. 

A form of hydrometer with a heavily loaded 
bulb at the bottom can be used if desired for 
testing a nickel-plating solution, the instrument 
being appropriately termed a nickelometer. To 
test a solution pour a quantity into a testing glass 
(any long, slender glass vessel will do) and gently 
lower the instrument into the sample. The nickelo- 
meter has a graduated stem, and the nickel solu- 
tion should not register less than seven degrees on 
this. If it does, more nickel salts must be added 
until the density of the solution is correct. 

Nickel anodes should invariably be made of 
pure rolled nickel plates of a thickness suitable 
to the work in hand. Small anodes for small 
operations should be thin, the thickness increas- 
ing with the superficial size of anode required. 
Plates of cast nickel are always clumsy, because 
heavy and thick ; they are also brittle and porous, 
whilst the pores are apt to contain impurities. 
Loose carbon, in the form of graphite, has been 
found interspersed with badly cast nickel. Rolled- 
nickel anodes give off the metal constantly and 
steadily ; they do not become soft or fall to pieces 
while in the bath as cast-nickel anodes do ; they 
may be light and thin to begin with, and they last 
a long time. Anodes of nickel may be suspended 
from strong hooks of copper, inserted in holes 
punched or drilled in the nickel plates. A suit- 
able hook is illustrated by Fig. 5 (p. 19), but 
Messrs. Canning and Co. offer the hook shown by 



I30 



Electro-pla ting. 



Fig. 62 as an improvement. This slides along the 
rods, and is very secure. 

It is advisable to coat all cycle fittings with 
copper before placing them in the nickel-plating 
\'at. Copper will adhere firmly to all metals if 
properly deposited, and fill in all cracks and 
blemishes, whilst nickel will adhere well to copper. 
It therefore performs the part of a solder in 
miiting nickel to other metals. Nickel may be de- 
posited firmly on iron and steel without the help 
of copper, but the process demands more skill, and 
the beginner does not produce such 
good results as when a coat of copper 
is first deposited on the fittings. The 
matter is fully discussed on pp. 90 
to 92. Copper may be readily de- 
posited on iron and steel from an acid 
solution of sulphate of copper, but 
the deposit of copper thus obtained 
will be useless for the present pur- 
pose, because it will not adhere 
firmly to the plated articles. When 
copper is deposited on iron and steel 
from an alkaline solution of copper, 
the deposit has a fine grain, and is 
firmly adherent to the article. The 
best alkaline solution for cycle 
plating is made as follows: — Esti- 
mate ^ lb. of copper sulphate for 
each gallon of solution required, and dissolve 
this salt in enough hot rainwater to form a 
solution. This will be about half a gallon of 
water to each pound of salt. Set this aside to 
cool, and when cold, add enough liquid ammonia, 
whilst stirring with a stick, first to throw down 
the copper in the form of green mud, and then 
dissolve this to form a beautiful blue liquid, free 
from sediment. Add to this enough cyanide of 
potassium dissolved in rainwater to destroy all 
the fine blue colour, and give the colour of old 




Fig. (;2. 

Improved 

Hook for 

Nickel 

Anode. 



Nickel-plating and Cycle-plating. 131 

ale to the solution. The quantity of liquid 
ammonia and of cyanide of potassium cannot be 
definitely stated here, as these materials vary 
very much in strength and quality ; hence, it is 
safest to follow the above colour indications, 
being careful to stir the solutions well after each 
addition of ammonia and of cyanide. 

For purposes of estimation take equal weights 
of each salt and the ammonia, as both are used 
for other purposes, if there should be a surplus. 
The solution thus formed should be well stirred, 
allowed to rest for a night, and then filtered 
through calico into the vat, where it is made up 
to the required quantity with rainwater. 

The coppering vat must be furnished with rods, 
anodes, cables, resistance-board, and other fit- 
tings, as before mentioned. 

In preparing new work intended to be plated, 
the work of the smith and fitter may be found 
either a help or a hindrance to the polisher and 
plater. Rough forgings, weldings, and brazings 
by an unskilled or careless smith cause an im- 
mense amount of extra labour to the plater's pol- 
isher. It may be stated emphatically here that all 
notions respecting the filling up and covering over 
properties of nickel are entirely erroneous and 
false. Nickel will not fill up cracks and deep 
pits, cuts, or file marks ; it will not cover defective 
forgings and rough welds. If the fitter does not 
file these out, they will be shown in the finished 
work, unless the polisher grinds out the flaws on 
the emery-wheel, and thereby weakens the part ; 
thus a defective machine is the result of a pol- 
isher's attempt to make good the faults of the 
smith. The smith should therefore aim at turn- 
ing out his part of the work in as smooth and 
finished condition as he can. The fitter should 
also be careful to avoid bruising or denting the 
surfaces of the parts, and leaving rough file-marks 
on them. He also should aim at turning out the 



132 Electro-pla ting. 

machine in a finished condition, remembering that 
the polisher's duty is to put on a higher finish, 
but not to make good the fitter's defects. 

The preparatory polishing of iron and steel 
parts of cycles may be done by hand with different 
grades of emery-cloth, but the work is best done 
in a polishing lathe or on an emery tape machine 
(see Chapter III.). When it is known that the 
surfaces of parts to be nickel-plated must be made 
as smooth and bright as iron and steel can be 
made before they are plated, the use of a machine 
to do this will be appreciated. The smallest 
scratch left by the smoothing file, or even by fine 
emery-cloth, will be plainly visible in the nickel 
coat even when this has been polished, for nickel 
is too hard and intractable to be scratch- 
brushed and burnished like copper, silver, or 
brass. 

If the forgings are rough, the rough parts 
must be taken down on an emery-wheel fastened 
to the spindle of the polishing lathe between 
suitable collars. Some skill is required in the 
use of these powerful tools, as they soon grind 
and cut their way into wrought-iron. The work 
must therefore be kept w^ell alive in front of the 
wheel, and not allowed to lie long enough for the 
emery to cut into the metal. Different shapes 
and sizes may be necessary to suit different forms 
of parts. 

When the rough patches are reduced, the work 
must next be submitted to the action of an emery- 
bob. If the work is not very rough, an emery- 
bob may be used from the first. For cycle work 
it is advisable to have an assortment of bobs, 
varying from 12 in. in diameter down to 9 in., 
6 in., and 4 in., and in various thicknesses, from 
2 in. to 1 in. ; also some solid bobs made of bull- 
neck or sea-horse, some of them only \ in. in 
thickness, and turned round on their edges to fit 
curves and hollows (see Fig. 34, p. 65). Coarse 



Nickel-plating and Cycle-plating. 133 

grain emery, such as No. 90, is used on bobs in- 
tended for the first grinding, then No. 120, or a 
finer grade, to take out marks made by the first ; 
then the work must be finished off or "coloured'' 
with flour-emery on a plain uncoated bob. The 
flour-emery must be mixed with a little oil, just 
enough to keep it from flying about, and allowed 
to pass between the work and the bob whilst this 
is revolving. 

The bobs are made to revolve toward the work- 
man, who stands in front, a little on one side, 
and holds the work to the revolving bob. The 
work must be kept well alive whilst polishing- 
that is, must be kept in continual movement, 
either from side to side or round and round in 
front of the bob, to prevent lines from being cut 
in the metal. It is somewhat difficult to guide a 
novice by instructions on paper, for there are 
many little acquired knacks known only to the 
practical polisher, and called up on the spur of 
the moment to meet some little requirement ; 
these knacks can only be obtained by practice. 
Polishing metal is generally designated dirty 
work, and the workman should protect his clothes 
by wearing a canvas apron or blouse overall ; 
but he may avoid much dirt by standing a little 
out of the line of particles flying off from the bobs. 

Copper, German silver, brass, and alloys of 
soft metals are not prepared with emery, but with 
a fine sand, sold under the name of Trent sand, 
applied on a clean bob. When the rough surface 
has been worn down with this sand, it is next 
subjected to the action of Tripoli composition ap- 
plied by a calico mop run on the spindle of the 
})olishing lathe. Tripoli composition is a com- 
position of Tripoli powder and tallow, and is sold 
in three grades — A, a fine grade for polishing 
nickel-plated goods, and putting the finishing 
polish on German silver, brass, copper, and other 
soft metals ; b is a grade not so fine as the pre- 



1 3 4 Electro-PL A ting. 

ceding, but will do for the same purpose where 
a highly-j&nished surface is not desired ; h is a 
harder and rougher grade, very useful in taking 
scratches and file-marks out of brass and copper 
before using the finer grades. These compositions 
are superior in every way to loose powder for 
polishing purposes. 

Surfaces about to be nickel-plated are given 
the finishing touch with a 9-in. calico mop charged 
wdth rouge composition, or with rouge powder 
mixed with water, or with fine powdered lime 
specially prepared for the purpose, and sold under 
the name of Sheffield lime. 

When the articles to be plated leave the pol- 
isher's hands, they are apparently as clean as it 
is possible to make them ; not a spot can be seen 
on the surface, which is clear and bright as a 
mirror. But this mirror-like surface will not re- 
ceive a coat of nickel, or, strictly speaking, will 
not retain the coat even should the plater get it 
on the article. This surface is coated with a very 
thin transparent film of animal matter, such as 
grease or oil, although it may have been finished 
with rouge and water or wdth lime, and this film 
will be quite enough to prevent the coat of nickel 
from uniting with the surface of the metal. Even 
one little spot in an obscure angle untouched by 
the scourer, will take on a loose coat of nickel, 
and form a blister, which will strip in the finish 
polishing, or after the article has been in w^ear for 
a few days. 

When the articles leave the polisher, they must 
therefore be first soaked in the hot potash solu- 
tion, to loosen and saponise the film of grease 
contracted whilst being polished, then rinsed in 
hot water to remove any loose soap and potash, 
and passed on to the scouring trough. A hold 
may be maintained on them during the dipping 
and rinsing processes by first twisting a stout wire, 
or two wires, if necessary, around them. Nuts, 



Nickel-plating and Cycle-plating. 135 

collars, rings, and similar articles with holes in 
them, may be strung on wires, but it is not ad- 
visable to bunch too many, as they are liable to 
scratch whilst being rinsed. 

The work to be scoured is held by the workman 
in his left hand on the edge of the scouring tray, 
or on a board provided for the purpose, whilst he 
scours it all over with a brush dipped in finely- 
powdered pumice-stone or finely-powdered whit- 
ing. Whiting is to be preferred, because it is not 
so rough as powdered pumice. Some workmen 
peg pieces of buff leather to the edges of the 
trays and scouring boards, to prevent scratching 
by the wood. Be sure to scour every little crevice 
of the article, and leave no part untouched, for it 
will be just this unscoured part which will strip 
after being plated. The work requires merely a 
brisk light brushing. Keep the left hand well 
coated with whiting, or handle the work with a 
clean linen rag to prevent soiling by SM^eat, for 
this will cause the nickel coat to strip. 

When every part has been well scoured, attach 
the slinging wires to each article as it is finished, 
rinse off all the whiting in one division of the 
trough, then in clean water contained in the next 
division, then in the hydrochloric dip for a few 
moments, again in clean water, and transfer at 
once to the copper-plating vat to receive a coat 
of copper, after which rinse and place in the 
nickel-plating vat. 

After the articles are scoured and rinsed — if 
made of iron, steel, zinc, Britannia metal, or 
pewter, and if the work of scouring has been 
done speedily — they may be transferred at once 
to the coppering vat. Whilst scouring large 
articles made of iron and steel, it is almost im- 
possible to prevent some parts from contracting 
a thin film of rust ; and this, if left on, would spoil 
the work by preventing close adherence of the de- 
posited coat. It is therefore advisable to dip 



1 3 6 Electro-pla ting. 

them for au instant in a solution of hydrochloric 
acid to remove the film of oxide thus contracted, 
then rinse them before placing them in the cop- 
pering vat. The vessel to contain this solution 
may be made of wood lined with lead, similar in 
all respects to the plating vat already described. 
The solution is composed of 1 part commercial 
hydrochloric acid (spirits of salts) in 5 parts of 
water. 

While brass, German silver, gun-metal, and 
similar alloys are being scoured, they also are 
liable to become tarnished on exposure to the air. 
It is therefore advisable to dip them in a solution 
of cyanide of potassium before placing them in 
the plating vat. There are not many or very 
large articles made for cycles in these metals, and 
so a small stoneware vessel will hold all the solu- 
tion required for this purpose. The solution con- 
tains \ lb. of commercial cyanide of potassium in 
each gallon of water. The cleaned articles are 
first swilled for a minute or two in this dip, then 
rinsed, and transferred at once to the plating vat. 
Copper must be treated in a similar manner. 

Lead alloys, such as pewter, Britannia metal, 
etc., are but seldom if ever used in the cycle 
trade ; when they are used, they are rinsed in the 
potash tank, and transferred from this direct to 
the coppering vat. 

The dynamo must be going, and the vat al- 
ready connected with it, before the articles are 
suspended in the nickel solution, for no time must 
be lost in starting the deposit after the final 
rinsing. Wherever practicable, each article should 
be suspended in the bath, so as to have the same 
quantity of solution above and below it — that is 
to say, it must be well bel-ow the surface, but not 
touching the bottom or the sides of the vat. It 
should also be slung with its surface facing two 
rows of anode plates — that is, with the nickel 
anodes all round, but not too close to the article. 



Nickel-plating and Cycle-plating, 137 

The switch on the resistance board should be well 
over, to include a high resistance when the first 
article is placed in the vat, then moved to a lower 
resistance when more articles are put in, because 
then more current is required. Put in large 
articles first, then sling smaller articles, such as 
nuts, collars, and screws, between them. If this 
order is not observed, the smaller things may 
strip whilst being polished. Steel should thus be 
flanked with iron, but it is not desirable to at- 
tempt plating copper, brass, German silver, and 
like alloys in a vat with iron and steel. These 
are best done by themselves. Small goods, when 
wired together, should have quite \ in. of space 
between each article, and screws are best wired 
with fine copper wire twisted around each, to 
form a long string of them. 

The work of deposition must go on without in- 
terruption for a period of from 1^ to 3 hours, 
according to the class of work to be done. It is 
sometimes necessary to turn the articles and move 
the slinging wires to prevent marking by the 
wires, but the goods should not be taken out ov 
the solution. 

When the article has been in the nickel-plating 
solution long enough to acquire the desired thick- 
ness of nickel, it is lifted out of the solution by 
means of the slinging wires, rinsed at once in the 
hot water tank, and immediately placed in the hot 
sawdust pan to dry off quickly. This celerity is 
necessary to prevent unsightly blotches and spots 
on the nickel-plated surface, as these show after 
the work has been polished. When a good de- 
posit of nickel comes out of the vat, it has a 
creamy white or a dull grey appearance, which 
passes to a creamy white when rinsed in hot 
water. Nickel deposited too fast or from an in- 
ferior solution may have a dirty grey appearance, 
which does not alter very much even when rinsed 
in hot water. To remedy this, add from one to 



138 El ectro-pla ting. 

two per cent, of common salt (sodium chloride) 
to the solution, and stir well together, then allow 
the disturbed sediment to subside during the next 
twelve hours. If the solution is allowed to dry 
on the surface, or if this is touched with the 
fingers whilst wet, dirty spots will be formed. 

The dried plated goods are now polished by 
means of suitable mops, dollies, and polishing 
materials. Nickel-plated articles may have their 
surface finished by polishing them with mops and 
dollies charged with Sheffield lime, with fine 
Tripoli composition, or with rouge composition. 
The lime employed for this purpose is a picked 
material, procured from Sheffield, where it is 
packed in casks and jars, from which air is ex- 
cluded, for transportation to other towns. It 
may be applied in the first place for polishing 
plane surfaces, together with a little oil, on a 
buff bob. When the rough surface has been 
brightened in this way, the bob may be removed, 
and replaced by a calico mop charged with lime, 
by holding a lump to it whilst it revolves. A 
good polish is thus obtained, which may be still 
further improved by using a dolly made of swan's- 
down calico, charged with dry lime from a lump 
held in the hand. An assortment of bobs, mops, 
and dollies should be kept on hand, including 
various sizes and varieties in shape, to go easily 
into curves and narrow grooves. 

A very good polish can be imparted to nickel 
by using first a basil leather mop charged with 
fine Tripoli composition, then a calico mop 
charged with rouge composition, and finally a 
swansdown calico dolly charged with rouge. 
This imparts a fine steely lustre to nickel-plated 
goods ; but the use of rouge on a lathe for polish- 
ing nickel-plated and silver-plated work has the 
disadvantage that the rouge flies about the shop, 
and gets into cracks and crannies, where the 
appearance of the red powder is objectionable, 



Nickel-plating and Cycle-plating. 139 

and from which it is with difficulty removed. It 
also penetrates the clothing of the workman, and 
gets into his hair. 

The work must be kept well alive in front of 
{ lie bob, mop, or dolly whilst polishing its surface — 
that is, it must be kept moving to and fro or up 
and down all the time, so as to prevent the tool 
from grinding into one spot, and cutting through 
the deposit. Special care must be observed when 
approaching sharp angles, the edges of holes, and 
sharp corners, as the nickel deposit is soon cut 
through at these points, and the work spoiled. 
The aim throughout is to get a bright mirror- 
like surface on the nickel ; and this is not very 
difficult if the work has been properly prepared 
for plating. If, however, the work has not been 
properly prepared, no amount of labour or skill 
will enable the finisher to turn out a polished 
surface ; and for doing the work over again, all 
the old nickel must be removed. One method of 
doing this is to steep it for a short time in 
commercial sulphuric acid, to which is added, 
from time to time, a small quantity of nitric 
acid. However, owing to the corrosive nature 
and fumes of the acid, the nickel is generally re- 
moved with emery bobs, the work being polished 
ready for plating at the same time. 

A large portion of the plating work to be done 
in repairing shops consists of replating the parts 
of cycles from which the nickel has been worn. 
This is not such easy work as plating new fittings, 
for the old parts are generally worn unevenly, 
dented, and bruised, and sometimes deeply pitted 
with rust. From the preceding instructions for 
plating new work, it will be clearly understood 
that all parts to be plated must be thoroughly 
cleaned ; and to do this, it is necessary to take 
the machine apart wherever a nut can be un- 
screwed, a screw withdrawn, or a key driven. 
All nuts, screws, collars, pins, and similar small 



1 40 ElectrO'Pla ting, 

articles, must be done apart from the larger fit- 
tings. Handles must be removed from handle- 
bars, and rubber from pedals and brakes, if these 
are to be plated, since the solutions will spoil all 
materials made of ivory, bone, horn, wood, rubber, 
vulcanite, . ebonite, etc., and the hot potash will 
loosen all handles. 

The loose dirt may be removed with a wisp of 
cotton-waste, and stiff grease should be taken off 
with some of the same waste dipped in turps. 
All parts to be plated should be thus roughly 
cleaned before they are sent to the polisher. If 
several parts of more than one cycle have to be re- 
plated, the smaller things, such as nuts, collars, 
pins, and small bolts, should be bunched together, 
tied with strings, and attached to the handle-bar 
of the machine to which they belong. 

As nickel-plated fittings are more or less tar- 
nished or stained with rust-marks when sent to the 
plater, it is advisable to first submit them to a 
leather mop, charged with emery or with coarse 
Tripoli composition, to clear the surface from 
stains and rust. It can then be seen whether they 
have been nickel-plated or not, and measures taken 
accordingly. If they have not been plated, and 
are merely polished iron or steel, rusted and 
stained, the polishing process must go on as for 
new parts, special attention being paid to rust- 
marks, which are sometimes very deep. If the 
parts to be nickelled have been previously nickel- 
plated, all the previous coat of nickel must Vje 
stripped off clean before a new coat can be firmly 
deposited on them. Nickel will not firmly adhere 
to a coat of nickel, even when freshly deposited 
and polished: hence the necessity of stripping it 
off before a new coat is laid thereon. 

A very thin coat of nickel may be ground off 
on an emery-wheel whilst preparing the article for 
polishing, but it is usual to take off nickel by 
means of an acid which will dissolve this metal 



Nickel-plating and Cycle-plating. 141 

without injuriously affecting the metal on which 
it is deposited. The stripping acid is composed of 
sulphuric acid, nitric acid, and water, mixed in the 
following manner: — In a stoneware vessel, cap- 
able of holding more than 12 gallons of liquid, first 
place 2 gallons of water; then add to this, in a 
cautious manner, 8 gallons of strong sulphuric 
acid, pouring it into the water in a thin stream, 
and stirring the mixture with a glass rod. This 
precaution is necessary, because the addition of 
this acid to water is always attended with an 
evolution of heat, and a consequent raising of the 
temperature of the liquid to almost boiling point. 
If water is added to the acid, instead of acid 
being added to water, the mixture will bubble as 
if boiling, and some of the scalding liquid will be 
spurted from the surface, with possibly serious 
results. After the sulphuric acid and water have 
been mixed, add to the mixture 2 gallons of com- 
mercial nitric acid, and stir all well together. 
As the heat generated in a mixture of sulphuric 
acid and water is liable to crack stoneware ves- 
sels, a lead-lined tank is preferable to stoneware 
for mixing the acids in ; but they must be trans- 
ferred to a stoneware vessel afterwards, because 
the mixture of nitric acid with sulphuric acid will 
dissolve lead. It will even dissolve enamel from 
iron vessels, and then violently attack the ex- 
posed iron. 

The articles to be stripped should be first 
cleaned free from grease and oil, swilled in the 
potash solution, and then in the hot-water tank, 
then wired with stout copper wires, and dipped 
in the stripping acid. If the coat of nickel is thin, 
it will be dissolved in a few moments. Thicker 
coats will take several minutes' immersion, and 
very thick coats may require half an hour's im- 
mersion. The work must therefore be closely 
watched, and lifted out occasionally for examina- 
tion, as each article should be removed from the 



142 Electro-pla ting. 

stripping acid, and plunged at once in clean cold 
water when the nickel has all been stripped off. 

As noxious fumes arise from the acid during 
the stripping process, this should be conducted in 
the open air, or in a recess provided with a flue 
and strong up-draught, to carry the fumes off 
from the operator. After the articles have been 
stripped and rinsed in cold water, they should be 
rinsed in hot water, dried in hot sawdust, and then 
prepared for plating in the manner already de- 
scribed. The subsequent operations for replating 
and finishing are the same as for new work. 

Some notes on the working of nickel-plating 
solutions will now be given. Nickel-plating solu- 
tions are always worked cold. 

The solution is at its proper working strength 
when it contains 1 lb. of nickel sulphate to the 
gallon of water. To maintain it at this strength 
attention must be paid to the anodes and their 
condition. As a rule, the surface of anodes ex- 
posed to the action of the solution should exceed 
by one-half the surface of the goods being plated. 
The anodes should also freely dissolve in the solu- 
tion, and therefore should not be too hard. 

If nickel has been drawn from the solution too 
fast, it will be liable to become too acid, and this 
condition may be ascertained by testing it with 
blue litmus paper, which will quickly redden if 
acid is in excess. But a slight excess is per- 
missible when plating iron and steel. An excess 
of acidity may be corrected by adding a small 
quantity of liquid ammonia ; but an addition of 
nickel sulphate wdll be required also if the normal 
strength of the solution has been reduced. The 
hydrometer will show this reduction by comparing 
it with a sample of known correct strength. The 
readings on the hydrometer scale show the density 
of the solution, but not its temperature. 

Sulphuric acid should not be added to a nickel- 
plating solution without previously testing the 



Nickel-plating and Cycle-plating, 143 

solution with litmus paper and finding it alkaline. 
Even then the acid should be added in very small 
quantities, and the solution stirred after each 
addition, then tested with litmus paper. The 
same caution should be exercised in adding ammo- 
nia if the solution is found to contain an excess 
of acid. Neutral solutions may be employed in 
plating copper and brass. 

If slimy yellow feathers appear on the anodes 
and on the sides of the vat, the solution is foul, 
deficient in nickel salts and their solvent. To 
alter this, filter all the solution through good 
calico, add one fluid ounce of sulphuric acid to 
each gallon, test for acidity with litmus paper, 
and add enough liquor ammonia to render the 
solution neutral. Work with nickel anodes greatly 
in excess of the surface to be coated. 

Pinholes in nickel plating are caused by small 
air bubbles left on the surface of the articles 
when immersed in the plating solution. These 
bubbles may be held in pinholes existing in the 
surface of the metal, or may form on the smooth 
surface itself. They may be broken by a smart 
tap on the edge of the article, by shaking it in the 
solution, or by sweeping the point of a feather 
over the surface. If the solution holds particles 
of dust, these may settle on the articles being 
plated and cause pinholes. To avoid this, keep 
the solution clean by filtering it occasionally 
through clean calico. 

Black streaks in deposits of nickel are caused 
by bubbles of hydrogen gas, which form in clusters 
on the surfaces of articles and then burst. They 
may be prevented by gently agitating the articles 
whilst being plated, or by stroking the clusters 
with a stout feather and thus bursting them. 

All electro-deposits of metal are slightly porous, 
and so when a thin deposit of nickel on steel or 
iron is exposed to moisture the tiny drops pene- 
trate these pores to the metal beneath and cause 



1 44 Electro-PL a ting. 

rust. A thicker deposit offers a better protection, 
or better still is a coat of copper deposited on the 
parts and well burnished previous to being coated 
with nickel. 

Aluminium may be treated much the same as 
zinc in preparing it to receive an electro-deposit 
of nickel or silver. After it has been well scoured 
with Trent sand, it must receive a coat of copper 
in a sulphate of copper solution, and be trans- 
ferred direct from this to the nickel-plating solu- 
tion. Solutions for nickel-plating on aluminium 
should not contain any free alkali, but he slightly 
acid, since alkalis act on aluminium. 

Nickel can be deposited on wax moulds, but 
previously the mould must be prepared with black- 
lead or with bronze powder as for the electrotype 
process, and a thin film of copper deposited upon 
it in an electrotype solution (1 lb. of copper sul- 
phate and 4 oz. of sulphuric acid in 1 gal. of rain- 
water). If the object desired is a copy of a de- 
sign impressed on the face of the mould, it will be 
advisable to remove the mould to the nickel vat 
when it has become coated with a very thin film 
of copper, and deposit the nickel on this film. If 
the design is not undercut, it may be possible to 
peel off the film of copper from the nickel ; but 
some difficulty may be experienced in getting a 
deposit of nickel thick enough to form a plate or 
sheet, as thick deposits have a tendency to crack, 
curl up, and peel off. To get a tough coat, the 
nickel should be deposited slowly with a low-ten- 
sion current. 



145 



CHAPTER VIII. 

FINISHING ELECTRO PLATED GOODS. 

Properly electro-deposited silver leaves the plat- 
ing solution with a pleasing, rough, creamy-white 
surface, much like fine unglazed porcelain. It 
should be rinsed in clean hot water to free it from 
silver salts, and may be dried in clean hot box- 
wood sawdust, or scratch-brushed first, then 
washed in warm soapsuds, rinsed, and dried to 
prepare it for the polisher. Great care must be 
taken of the surface, as it is easily soiled and 
readily tarnished, and then causes much trouble 
to the polisher and finisher, who will have some 
difficulty in cleaning the surface. The rinsing 
waters must therefore be clean, and the sawdust 
free from dirt and burnt or brown particles. 
Should the article have a yellowish tinge when 
taken from the vat or from the hot sawdust, swill 
it at once in a warm dilute solution of potassium 
cyanide and rinse and dry 

If the silver-plated surface is to have a higher 
polish than that imparted by scratch-brushing, it 
must next be held against a revolving swansdown 
mop charged with fine rouge. This may be applied 
in the form of powder to a mop previously 
greased or oiled ; but rouge compositions do the 
work better, and in working are far more cleanly 
than powdered rouge. Avoid rubbing the silver 
off angles and projections, and apply pressure 
moderately, the surfaces being kept moving to and 
fro to prevent the mop cutting into one spot. This 
movement is specially necessary when polishing 
the coat on soft metals, to prevent blistering, as 



146 Electro-plating. 

the heat generated by friction is liable to cause 
buckling of the underlying metal. 

Deeply impressed or engraved designs to be 
highly polished must be held against a revolving 
hair-brush charged with rouge powder. 

AVhen a sufficiently high polish has been ob- 
tained, it is advisable to wash out any rouge that 
may have lodged in crevices by steeping the 
articles in hot soapy Avater and mopping with a 
soft woollen mop. After this they should be 
rinsed in hot water and dried, then mopped with 
a clean swansdown mop. With great care in 
keeping mops free from grit, dust, dirt, etc., and 
the use of best quality compositions, a high lustre 
can be got on silver-plate by mopping alone. 

If the deposit blisters and breaks away whilst 
being scratch-brushed, the loose silver must be 
all got off, either by means of a rough bob or in 
a stripping solution, and the surface again pre- 
pared by polishing, scouring, and quicking as 
before. The thin preparatory coat may be thus 
ground oft" easily without blotching the surface ; 
but if the deposit blisters at a later stage it will 
be necessary to strip off all the silver in acid and 
begin afresh to get a good surface. The articles 
to be stripped must be quite dry and attached to 
stout wires, then gently moved in ordinary un- 
diluted sulphuric acid made hot in a stoneware 
vessel, and grain saltpetre added in small quan- 
tities at a time until all the silver has been dis- 
solved. If this is done carefully the acid will do 
very little injury to the article. For large articles 
a cold stripping solution may be employed ; this 
is composed of sulphuric acid with a little nitric 
acid added from time to time as required. 

Small articles, such as buckles, buttons, metal 
beads, hooks and eyes, etc., are treated in a 
special manner in preparing, silvering, and finish- 
ing. They are prepared by shaking some hundreds 
at a time with grit and sawdust in a revolving 



Finishing Electro-plated Goods. 147 

barrel or in a stout sack. If it is necessary to 
pickle them, they are massed together in a per- 
forated acid-proof vessel and shaken in this whilst 
immersed in the pickles and rinsing waters. 
Whilst being plated they are held in a basket 
made of brass or copper wire, and this is also to 
be kept moving by shaking to prevent contact for 
a long time ; if this is not done, the articles will 
be blotched where they touch each other. By 
automatic machines the articles are so kept in 
motion whilst being plated that they are in a 
polished condition when the silvering is finished. 
If these machines are not employed, the articles 
must be rinsed and dried, and then polished by 
shaking together with sawdust or bran. 

With regard to finishing gold-plated work, 
strongly gilt articles just taken from the gilding 
solution will be found to be coated with a brown 
powder. This powder is finely divided gold in a 
crystalline condition, the mass of crystals absorb- 
ing, instead of reflecting, the light. To remove 
tliis brown appearance, the articles are briskly 
scratch-brushed, the scratch-knot lathe being a 
convenient appliance for this purpose. The ends 
of the brass wires wear down the points of the 
gold crystals, and render the whole surface 
smooth. To prevent the brass from wearing off 
in the shape of dust and cutting the gold coat, Ihe 
brush is kept lubricated with stale beer, and is 
covered with a hood, to prevent the lubricant from 
being splashed over other things in the workshop. 
Rest the w^ork on a sloping piece of board over a 
vessel placed so as to catch the drips of stale beer, 
and work the brush from left to right, away from 
the workman, going over all the surface until all 
the brown appearance has been removed. Do not 
leave any of this in the crevices. Lastly, rinse 
the work in warm water, and dry it in hot box- 
wood sawdust. Then polish with dry rouge on a 
plate brush, or burnish w^ith a highly polished steel 



1 48 Electro-pla ting. 

burnisher, or one of highly polished bloodstone, 
using newly made soapsuds as a lubricant. 

Stale beer, as stated on the preceding page, is 
employed as a lubricant whilst scratch-brushing 
electro-plated articles. Unless a lubricant is used, 
the brass of the brush wire gets worn off as fine 
dust and becomes embedded in the surface of the 
plated article, rendering it more or less brassy in 
appearance. A tea made of marsh mallows, or 
weak linseed tea, can be used instead of the beer. 

A still higher polish on electro-plated work re- 
sults from the use of steel, agate, and bloodstone 
burnishers. These tools are made in a large 
variety of shapes to suit all possible surfaces. 
The steel burnishers have very highly polished 
rubbing surfaces, which must be maintained in 
this condition by frequent rubbings on a pad of 
buff leather charged with putty powder. Skill in 
burnishing is acquired only by practice. The 
article is held on a soft pad with one hand, whilst 
the burnisher is held firmly by its handle with the 
other hand, and pressed hard on the surface with 
uniform straight strokes slightly overlapping each 
other. The surface of the burnisher may be kept 
moist with soapsuds, made either Avith best soap 
or with special burnishing soap. After the steel 
burnishing, the finish is imparted with either agate 
or bloodstone burnishers, and the whole article 
afterwards rinsed in hot water, then dried by 
rubbing with a soft linen cloth free from dust. 
The mirror-like surface of burnished silver is easily 
scratched and soiled, and should not be wiped or 
handled more than necessary. Soft metals, sucli 
as pewtoi', must be burnished very lightly, if at all. 

Burnishers in their least expensive form are 
made of steel blades varying in shape, running 
into the wood. Straight burnishers, shaped as 
shown at Fig. 63, and in section at A, are used for 
burnishing stems of spoons and forks, and plane 
surfaces generally. Curved burnishers, such as 



Finishing Electro-plated Goods. 



149 



those shown in Figs. 64 to 68, and in section at 
B, c, D, E, and F, are used for burnishing the 
insides of the bowls of spoons and for hollow 
curves. Burnishers made of chips of agate, and of 
bloodstone or haematite, set in brass ferrules and 
mounted on wood, are more costly than those 
made of steel, and they also impart to the goods 
a more finished surface. Some further forms of 





^" ^) c 

Fig. 63. Fig. (U. Fig. C. 

Fi<r, 03. — Straight Burnisher 



Burnishers. 



Fig. (;»]. Fig. 07. 

Figs. Gt to 6r).--Curved 
(57. — Round Burnisher. 



burnishers in everyday use are shown in Figs. 
69 to 72. Special agate burnishers are illustrated 
by Figs. 73 to 76. 

Buffs are used to impart a perfectly smooth 
polish to steel and bloodstone burnishers. When 
used for this purpose, the strip of buff leather is 
first boiled in water and dried quickly, then glued 
to a flat piece of wood a little larger than itself, 



ISO 



Electro-pla Tim 



/incl weighted with heavy weights until quite firm. 
The bufL' then resembles a mounted hone or oil- 
stone, such as is used by carpenters (see Fig. 77). 
It is most important that the work to be bur- 
7iished should have been prepared properly for 
plating, as on this depends the perfection of the 
burnished surface. In the first place, all scratches, 
lines, indentations, and corroded pits must be re- 




:1 



Fi<?. (".8. Fig-. 60. Fig. 70. Fiy. 71. Fig-. 72. 

Fig. 68.— Hooked Burnisher. Fig. 69.— Curved Burnisher. 
Fig. 70. — Burnisher for Corners, etc. Fig. 71. — Hooked 
Burnisher. Fig. 72. — Pointed Burnisher. 

moved by filing, rubbing down with water of Ayr 
stone, polishing, and burnishing, before the 
article is pickled and quicked with mercury pre- 
paratory to being placed in the plating vat. The 
slight roughness imparted to the surface by the 
action of the acid pickle is not in any way detri- 
mental, but should a stain be left on the brass or 
German silver surface, or should the operator 
leave his finger-marks upon it, these will be dis- 



Finishing Electro-plated Goods. 



151 



tinctly traceable in the surface of the finished 
article, even if the spot does not strip under the 
burnisher. The utmost cleanliness must be ob- 
served in the preparation of the articles to be 
burnished, and care must be taken to put the 
quicking coat of mercury on evenly, or the silver 
\vill be apt to strip from slightly soiled spots, as 
also from those where thick blotches of mercury 
have been left on the surface. 



I 



Fig. 73. Fio-. 74. 

Figs. 73 to 70.- 



Fig. 75. 
-Agate Burnisliers 




Articles made of pewter, Britannia metal, and 
similar alloys are usually difficult to burnish be- 
cause they are softer than the overlying coat of 
silver, but they are made worse by lack of care 
in their preparation ; they should be transferred 
at once from a clean potash dip to the plating 
solution (after being properly cleaned and pre- 
pared) without any intervening rinsing, because 
such alloys are readily tarnished when exposed 



152 Electro-platim;. 

to the air whilst wet. Potash dissolves the 
tarnish. 

Silver will strip under the burnisher when it 
is deposited too fast or too slow, since its hard- 
ness is greatly affected by its rate of deposition. 
The plater should, therefore, find out by trial the 
best rate at which to deposit a coat for burnishing 
on the several metals or alloys likely to be em- 
ployed. Silver will also strip when a plating bath 
has been made up by dissolving chloride of silver 
in a solution of cyanide of potassium, or when 
chloride of silver has been used in building or 
faking up a plating solution. A similar result will 
follow on the use of too much brightening solution 
in the plating bath. Plating solutions thus ruined 
should be set aside for the most common work, 
allowed to work out, and then treated for re- 
covery of silver. 

Work that is to be burnished should be laid on 
a clean soft pad of rag, on which it w411 be held 
during the process. 

If an attempt were made to burnish articles 
whilst the surface and the burnisher were dry, 
the tool would heat and drag off the silver in the 
form of fine dust. A lubricant is, therefore, 
essential ; linseed tea or a decoction of marsh 
mallows answer this purpose, as both of these are 
of a slippery nature, and are harmless when 
applied to silver. Soap-suds are sometimes used, 
and these form a fairly good substitute when 
freshly made, but they should never be set aside 
for use a second time, as they are apt, whilst 
standing exposed to the air, to undergo chemical 
changes which result in the formation of acids 
injurious to the silver coating. 

The burnisher must first be polished to a dead 
black lustre, by rubbing its edge or face briskly 
along a groove worn in a polishing buff charged 
with jeweller's rouge. A thin burnisher is first 
selected to ground the work, which is afterwards 



Finishing Electro-plated Goods. 153 

gone over with one having a broader surface, 
finally finishing off with a broad bloodstone bur- 
nisher. The tool is held in the right hand, the 
lower part of the handle resting on the outside 
of the little finger, and the upper part resting 
against the inside of the three other fingers, with 
the ball of the thumb on the top of the handle. 
In this position great pressure can be brought to 
bear upon the tool, if required. 

The strokes of the burnisher always should be 
given in one direction, since cross strokes will 
spoil the appearance of the burnished surface. 
Each stroke must be applied with some pressure, 
and the burnisher must be kept supplied freely 




Fig. 77. — Buff for Polishing Burnishers. 

with the lubricant, to prevent heating. Each suc- 
ceeding stroke should slightly overlap that of its 
predecessor, so as not to leave unburnished metal 
between the strokes, and a clear, mirror-like sur- 
face behind. As the surface or the edge of the 
burnisher gets dull by use, polish it up on the 
buff, which is charged with rouge or with the finest 
putty powder. Very pleasing effects on orna- 
mental goods are sometimes obtained by burnishing 
certain parts, such as bands and raised parts, 
whilst others are left matt. Gold-plated articles 
are treated in a similar manner to those of silver, 
but it is not usual to burnish nickel, since this 
uietal is somewhat hard and intractable under the 
burnisher. When articles have been burnished, 
the finishing polish is put on by hand with soft 
rags, charged with a suitable plate powder, or by 
a dolly of soft linen revolving in a lathe. 



154 



CHAPTER IX. 

ELECTRO-PLATING WITH VARIOUS METALS 
AND ALLOYS. 

To make an electro-tinning solution suitable for 
small brass and iron articles, dissolve 1 lb. of 
common washing soda, ^ lb. of best pearlasb, 
1^ oz. of caustic potash, and 1 dr. of potassium 
cyanide in 1^ gal. of warm rainwater ; then add 
5 lb. of tin peroxide and 1 dr. of zinc acetate, well 
stir until all is dissolved, and filter through a piece 
of calico. This solution should be kept in a 
stoneware vessel immersed in hot water in an 
outer vessel of metal, as it will have to be kept 
at a temperature of 75° F. whilst working. Use 
an anode of pure tin and work with a current at 
not more than 4 volts. Add small quantities of 
caustic potash and potassium cyanide as may be 
required to keep the anode and solution in work- 
ing order. 

A solution for the electrical deposition of iron 
has been made by dissolving, in 200 cubic centi- 
metres of distilled water, 10 gram, of yellow prus- 
siate of potash and 20 gram, of Rochelle salts. 
Then add a solution consisting of 3 gram, of per- 
sulphate of iron and 50 cubic centimetres of water. 
To make this ready for use, a solution of caustic 
soda is added very slowly, keeping the whole well 
stirred, until a clear yellowish liquid is obtained. 
Another solution, also due to Boettger, is pre- 
pared by evaporating and crystallising equal parts 
of sulphate of iron and sulphate of ammonia. 
A solution of the double salt is made, which, 
when current is passed, yields a good white de- 
posit of iron. 



Electro-plating with Platinu^^f. 155 

Iron-plating solutions may become exhausted 
9f metal from insufficient anode surface and the 
oxidising effect of the atmosphere. The anode 
surface should be very greatly in excess of ap- 
parent requirements, best soft charcoal iron being 
used. This is necessary because the solution does 
not readily dissolve iron, and even a faint current 
deposits the iron on the cathode faster than it can 
be dissolved from the anodes. Again, iron solu- 
tions exposed to the action of air absorb oxygen 
from the atmosphere, and the oxidised iron falls 
to tlie bottom of the vat. Covering the smface 
with a film of glycerine helps to protect it from 
atmospheric effects. Keeping ,a faint current 
passing through the solution to a small cathode 
counteracts these effects. 

A solution for the electro-deposition of plati- 
num is not easy to work, but may be made thus : 
In a porcelain capsule dissolve 1 oz. of platinum 
scrap in a hot mixture of 1 part nitric acid and 
2| parts of hydrochloric acid. Continue with a 
gentle heat until all excess acid has been 
evaporated, and the solution assumes the consis- 
tency of thick blood-red syrup, then allow this to 
cool and solidify. Next dissolve this deep red salt 
(platinum tetrachloride) in hot distilled water, 
allow the solution to cool, and filter through 
blotting-paper. Add a strong solution of potas- 
sium cyanide to this until it acquires a clear 
amber tint, then make up to 1 gal. with distilled 
water. Make up the bath in a vessel of enamelled 
iron, commence w^orking at a temperature of 
112° F. with current from one cell of any battery, 
and note results. If good platinum is obtained 
from this moderately warm solution with a feeble 
current, continue to work it ; but if the deposit 
is not satisfactory, raise the temperature and 
increase the current by using twx) cells in series. 

Platinum solutions demand attention and care- 
ful adjustment of temperature and current. As a 



156 Electro-PL A ting. 

rule, they work best when they contain 1 oz. of 
platinum in each gallon of liquid ; but, as the 
platinum anodes do not dissolve to feed the solu- 
tions and thus make up for metal withdrawn from 
them in deposition, they are continually altering 
in strength and density. To counteract the effects 
of this alteration, it is necessary to increase the 
current and raise the temperature of the solution, 
or to add enough concentiated solution of the 
double salt of platinum and cyanide to keep the 
bath up to its original strength. 

To make a solution for depositing lead, dis- 
solve 1 lb. of acetate of lead in 1 gal. of water, 
and add cyanide of potassium to precipitate the 
lead as lead cyanide, and then enough cyanide 
to re-dissolve this, and also to form free cyanide. 
Work with a pure lead anode and two Bunsens. 

A brassing solution for use cold is made with 
4 oz. each of carbonate of copper and carbonate 
of zinc recently prepared ; 8 oz. each of carbonate 
of soda in crystals, bisulphate of soda, and pure 
cyanide of potassium ; -^^ oz. of white arsenic ; 
and about 2 gal. of water. Dissolve in water the 
copper carbonate and the zinc carbonate, and then 
add the soda carbonate and soda bisulphate. Dis- 
solve in warm water the cyanide of potassium and 
the white arsenic, and pour this liquid into the 
other, which becomes rapidly decolorised ; add 
distilled w^ater to make 2 gal. or slightly more. 

The follow^ing is another method of making an 
electro-brassing solution. Procure 4 fluid oz. of 
nitric acid and dilute it with 2 fluid oz. of distilled 
water; heat the mixture in a glass or porcelain 
vessel under the influence of a good draught, and 
add cuttings of sheet brass until the acid ceases 
to dissolve. Dilute this with four times its bulk 
of rainwater, and add liquid ammonia, stirring 
until the green precipitate first formed has been 
all dissolved, and a clear blue liquid only remains. 
To this add a strong solution of potassium cyanide 



Electro-plating with Brass and Bronze. 157 

until the liquid changes in colour from blue to 
pink ; then add more cyanide cautiously, stirring 
until it assumes an amber tint. Allow it to stand 
like this for twenty-four hours ; then filter the 
clear liquid through calico into the vat in which 
it is to be used. Work with a good sheet brass 
anode. 

Electro-brassing solutions are known in great 
variety, the two just given being among the best 
of twenty or more. 

The electro-deposition of bronze itself is rarely 
practised, since most brassing solutions can be 
made to yield a deposit resembling real bronze in 
tint, by merely increasing the quantity of copper 
ill the deposit. Electro-bronzing can also be done 
with an alkaline coppering solution made as 
follows : Dissolve 2 oz. of copper sulphate in 1 qt. 
of hot water ; add this to \ gal. of rainwater con- 
taining 4 oz. of potassium carbonate ; then add 
2 oz. of liquid ammonia, and stir until the green 
precipitate has been dissolved ; mix this liquid 
with a solution of 6 oz. of potassium cyanide in 
\ gal. of rainwater, and filter for use. This solu- 
tion is best worked at a temperature of 100° F., 
but can be worked cold, with current at a pressure 
of from G to 9 volts. It deposits a bronze-coloured 
copper at low temperatures with the higher vol- 
tage. The bronze tint may be deepened by rins- 
ing the coppered goods in a solution of sal- 
ammoniac. 

[Many of the blocks in this book illustrating 
electro-platers' appliances have been kindly lent 
by Messrs. W. Canning and Co., Great Hampton 
Street, Birmingham, and Mosxi s. J. E. Hartley 
and Son, St. Paul's Square, Birmingham.] 



INDEX. 



Acid Pickles, 73 

Agate Burnishers, 143, 149 

Aluminium, Copper-plating, 99 

, Gold-plating, 118, 123 

, Niclcel-plating, 144 

American Nicliel-plating, 128 
Ammeter, 49, 54 
Anion, 10 
Anode, 9—12 

, Soluble and Insoluble, 10 

—12 
Anodes for Copper-plating, 93 
Gold-plating, 112 

Nickel-plating, 128 

Silver-plating, 83, 84 

Balances, 20—23 
Baskets, Dipping, 73 
Batteries, 24—42 

, Bunsen, 25, 28—30 

, Coupling, 42 

, Daniell, 25—23 

for Gold-plating, 103 

, Frencli Bunsen, 25, 30 

, i\iller, 56, 37 

, Gassner, 37—39 

- — , Large, 42 

• , Leclanche, 39—42 

, Smee, 25, 26, 30, 35, 36 

, Walker, 25, 26, 30 

— , Wollaston. 30—35 
Battery, Negative and Positive 

Elements of, 10 
Beads, Gold-plating, 122 
Beakers, 23 
Bench, Dynamo, 48 

Polishing Lathe, 57, 58 

, Scouring, 18 

Bobs, 60—63 

Brass, Plating witli, 156, 157 

■ , Preparing, for Plating, 72 

Bronze, Plating with, 157 
Brooches, Gold-plating, 120 
Brushes, Circular, 66 

, Potash, 67 

, Scouring, 66, 67 

, Scratch (see Scratch- 

bruslies) 

■ , Woollen, 66 

Buff Stick, G3, 64 
Buffs, 60—63 

for Burnisliers, 149 

Burnishers, 148, 149 
Burnishing, 148—153 
Bunsen Batterv, 25, 28—30 
Burner, 20 

Cables, 50, 51 

Calico Mops, 64—66 

Canning's Dynamo, 46—48 

Carbon, Copper-plating, 97 

Carvings, Copper-plating, 98 

Cathode, 12 

Chains, Gold-plating, 112, 122 



Chamois Leather Mops, 64 
Circular Brushes, 66—70 
Commutator, Dynamo, 50 
Copper Hooks, 19, 20 

-, Preparing, for Plating, 72 

Copper-plating, 90—100 

Aluminium, 99, 100 

, Anodes for, 93 

before Nickel-plating, 90— 

92, 130 

Silver-plating, 75 

Carbon, 97 

Carvings, 98 

, Current for, 94 

Earthenware, 97, 98 

: Finishing, 96 

Iron and Steel, 94, 97 

Lead, 95, 96 

Plaster, 98 

— , Preparing Articles for, 94 

Solutions, 76, 92, 93, 130 

, Care of, 93 

Terra-cotta, etc., 97—99 

— - Tin, 95 
•— Zinc, 95 

Cruet, Silver-plating, 84. 85 

Cvanide of Potassium, 77, 82 

Silver, 79 

Cycle, Taking apart, for Plat- 
ing, 139 

Cycle-plating, 125 — 142 {see also 
Nickel-plating) 

Daniell Battery, 2&— 28 

Dents, Removing, 74 

Dipping Baskets, 73 

Dollies (see Mops) 

Dynamo, Adjusting, 49 

, Advantages of, 24 

Bench, 48 

Brushes, 49, 50 

-— Cables, 50, 51 

, Canning's, 40—48 

, Care of, 50 

Commutator, 50 

, Driving, 48, 49 

, Electric Lighting, 43 

, Hartley's. 44, 45 

, Making, 46 

for Plating, 42—50 

', Position of, 48 

, Starting, 49 

Earthenware, Plating, 97 

Electric Connections, 45, 55 

Electrolysis. 9, 10 

Electro-plating, Principle of, 9 

Emery, 60, 63 

Tape Machine, 63 

Wheel Machine, 60 

Felt Bobs, 60—65 

Finisliing Plated Goods, 145 

French Bunsen Battery, 25, 30 

Fuller Battery, 36, 37 



Index, 



159 



Gassner Battery, 37—39 
Gilding-metal, 104 
Gold-plating, 101—124 

Aluminium, 118, 123 

■ , Anodes for, 112, 113 

— - Beads, 122 

: Calculating Amount of 

Deposit, 119, 120 

■ Chains, 112, 122 

: Colour of Deposited Gold, 

106, 113—117 

in Colours, 117 

■: Finisliing, 119, 147, 148 

, Frosted Effect in, 104, 119 

Iron and Steel, 103, 118 

Jewellery, 120—124 

■ Lead. 104 

-— Lockets and Brooches, 120 

, Matt Effect in, 104, 119 

Mugs, 118 

-: Obtaining Thick Deposit, 

117 

Outfits, Small, 101—103 

Pewter, 104 

, Preparing Articles for, 

103, 104. 120 

■ Salt Cellars, 118 

, Scratch-bruslies for, 118 

, Simple, 101 

: Slime on Anodes, 113 

Soldered .Toints, 124 

Solution, 101, 104—112 

— , Alloyed Gold in, 112, 

113, 117 

• , Cheap, 111 

, (.'opper in, 106 

, Exhausting, 105 

, Gold for Making, 106 

, Roseleur's. Ill 

, Working, 114 - 116 

■ Spoons, 118 

Trinkets, 120—124 

Vats, 103 

, Wiring Articles for, 112 

■ Zinc, 104 

Grease, Removing, 71, 73 
Grinding Machines, 58—60 
, Using, 151—133 

Hartley's Dynamo, 44, 45 
1 looks, 19, 20, 129 

Iron, Copper-plating, 94, 97 

, Gold-plating, 103 

■ , Plating with, 154, 155 

, Silver-plating, 75 

Jewellery, Gold-plating, 120 
, Silver-plating, 88, 89 

Lacquered Goods, Plating, 72 
Lathes, Polishing, 56-59 

■ •, Scratch-knot, 70 

Lead, Copper-plating, 95, 96 



Lead, Gold-plating, 104 

, Plating with, 156 

, Silver-plating, 75, 85 

Leather Bobs, 60—63 

- Mops, 64 
Leclanche Battery, 39—42 
Leyden Jars, 24 

Lime, Sheffield, 60, 138 
Litmus Paper, 129 
Lockets, Gold-plating, 120 
Lubricant for Burnishing, 152 

Scratch-brushing, 148 

Macliines, Grinding and Polish- 
ing, 58—60 

, Emery Tape, 63 

, Wheel, 60 

Mops or Dollies, 64-66 
Mugs, Gold-plating, 118 

Nickel-ammonia Salt, 123 
Nickelometor, 129 
Nickel-plating, 125—144 

Aluminium, 144 

, American, 128, 129 

■: Anode Hooks. 129 

, Anodes for, 129 

, Black Streaks in, 143 

, Copper-plating before, 90 

-92, 130 

, Pinholes in, 143 

Plant, 125—127 

: Polishing Plated Goods, 

138, 139 

, Porosity of, 143, 144 

— -, Preparing Articles for, 

131—136, 140 

- -, Process of, 136, 137 

Solution, 127, 128 

— , Care of, 142, 143 

, Correcting Acidity 

of, 128, 129 

, Stripping, 140—142 

, Taking Machine Apart 

for, 139 

Wax Moulds, 144 

Nitrate of Silver, 79 

Oertling Assay Balance, 21 

Pan, Sawdust, 20 
Pewter, Gold-plating, 104 
Piles or Batteries, 26 
Pinholes in Nickel-plating, 143 
Plaster, Copper-plating, 98 
Plating Balance. 21—23 

Bath, Small, 18 

Shop, 13, 14 

Vat, 16 

• ■ Rods, 51, 52 

Stand, 18 

Platinum, Plating witli, 155 
Polishing Lathes, 56—59 
, Bench, 57, 58 



i6o 



Index. 



Polishing Lathes, Speed of, 56, 

57 
, Spindles of, 58, 59 

, Steam Power, 56 

, Using, 131—153 

Materials, 60 

Metals, 56 

Plated Goods, 145—153 

Potash Brushes, 67 

• Solution, 75 

Tank, 14 

, Heating, 15 

Potassium Cyanide, 77, 82 

Quicking, 75—77 

Resistance Board, 52 — 54 
Rods over Plating Vat, 51, 52 
Rottenstone, 60 

Roseleur's Gold-plating Solu- 
tion, 111 

Plating Balance, 22, 25 

Rust, Removing, 72 

Salt Cellars, Gold-plating, 118 

Sand, Trent, 60 

Sawdust Pan, 20 

Scales or Balances, 20—23 

Scouring Bench, 16 

Brushes, 66, 67 

Trough. 15 

Scratch-brushes, 67—70, 118 

, Lubricant used with, 70 

, Using, 70 

Scratch-brushing'; 145—147 

, Lubricant for, 148 

Scratches, Removing, 74 
Scratch-knot, 68 

Lathe, 70 

Sheffield Lime, 60, 138 
Shop, Plating, 13, 14 
Silver Cyanide. 79 

Nitrate. 79 

Silver-plated Goods, Blistering, 

146 
■ — — , Drying, 84 

- — , Finisliiug, 145 — 155 

, Scratch-brushing, 145 

Silver-platinc;, 71—89 

, Anodes for, 83, 84 

, Bright, 87, 88 

Britannia Metal, 75. 85 

: Colour of Deposited Coat, 

79 

Cru.'t, 84. 85 

■, Current Required for, 77 

Inside of Teapot, 86 

Iron and Steel, 75 

Jewellery, 88, 89 

Lead. 75, 85 

Pewter, 75 

: Preliminary Copper-plat- 
ing, 75, 76 



Silver-plating, Preparing Arti- 
cles for, 71—77 

, Quicking Articles for, 75 

: Rate of Deposition, 78 

Solution, 79—82 

, Action of Light upon, 

83 

, Amount of Silver in, 

80 

, Care of, 82 

, Muddiness of, 82 

• Small Articles, 88 

, Stripping, 145, 146 

Tin, 85 

: Weight of Silver De- 
posited, 89, 119, 120 

: Wiring Articles, 75 

■ Sword and Sheath, 86, 87 

Zinc, 75 

Slinging Wires, 19 

Smee Battery, 25, 26, 50, 35. 36 
Soldered Joints, Plating, 124 
Spoons, Gold-plating, 118 
Steel Burnishers, 148, 149 

, Copper-plating, 94. 97 

, Gold-plating, 103, 118 

, Silver-plating, 75, 86 

Stick, Buff, 63. 64 

Stripping Nickel-plating, 140 

Silver-plating. 145. 146 

Swansdown Mops, 64, 66 
Sword, Silver-plating, 86, 87 

Tank, Hot-water. 15 

-, Potash, 14. 15 

, Sawdust, 20 

Tarnish, Removing, 75 
Teapot, Silver-plating, 86 
Terra-cotta, Copper-plating, 97 
Tin, Copper-plating, 85 

, Plating with, 154 

, Silver-plating, 85 

Tray, Scouring, 15 

Trent Sand, 60 

Trinkets, Gold-plating. 120—124 

Tripoli Composition. 60, 133 

Trough, Scouring, 15 

Vat for (iold-plating. 103 

, Plating, 16-19 

, , Stand for, 18 

Verdigris, Removing, 72 
Volt a, 26 
Voltmeter, 54 

Wax, Nickel-plating, 144 
Walker Battery, 25; 26, 50 
Wires, Slinging, 19 
Wood, Copper-plating, 98 
Woollen Brushes, 66 
Wollaston Battery, 30—35 

Zinc, Copper-plating, 95 
, Gold-plating, 104 



Printed by Cassell & Co., Ltd., Ludgate Hill, London, E.G. 



ENGINEER'S HANDY-BOOK. 

CONTAINING 

FACTS, formula:, tables and questions 

ON POWER, ITS GENERATION, TRANSMISSION AND MEASUREMENT; 
HEAT, FUEL AND STEAM; THE STEAM-BOILER AND ACCESSORIES; 
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RULES FOR CALCULATING SIZES OF WIRES. 

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FIFTEENTH EDITION. 

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■ Ex-President of the Electrical Section of the Franklin Institute. 



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<]\ DAVID McKAY, 

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TECHNICAL INSTRUCTION. 

Important New Series of Practical Volumes. Edited by PAUL 
N. HASLUCK. With numerous Illustrations in the Text. 
Each book contains about 1 60 pages, crown 8vo. Cloth, 
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Practical Draughtsmen's Work. With 226 Illustrations. 

Contents. — Drawing Boards. Paper and Mounting. Draughtsmen's Instru- 
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Projection. Back Lining Drawings. Scale Drawings and Maps. Colouring 
Drawings. Making a Drawing. Index. 

Practical Gasfitting. With 120 Illustrations. 

Contents — How Coal Gas is Made. Coal Gas from the Retort to the Gas 
Holder. Gas Supply from Gas Holder to Meter. Laying the Gas Pipe in the 
House. Gas Meters. Gas Burners. Incandescent Lights. Gas Fittings in 
Workshops and Theatres. Gas Fittings for Festival Illuminations. Gas Fires 
and Cooking Stoves. Index. 

Practical Staircase Joinery. With 215 Illustrations. 

Contents. — Introduction : Explanation of Terms. Simple Form of Staircase 
— Housed String Stair : Measuring, Planning, and Setting Out. Two-flight 
Staircase. Staircase with Winders at Bottom. Staircase with Winders at Top 
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of Plane Figures. Geometrical Construction and Development of Solid 
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